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Due to various reasons, variabilities in freight train travel time may be significant, yielding considerable challenges to forecasting the estimated time of arrival (ETA). Based on historical railway ETA data, this study first analyzes the shared route, then converts the historical data information of a train into multiple time data points, and finally, builds a tree-based model selection framework using the random forest algorithm (RF) and a feature weighted K-nearest neighbor algorithm (FWKNN) to create a phased prediction model. In terms of time, we study the use of different algorithms to predict the ETA of freight trains at various locations on freight train routes. In this study, the proposed method was tested on the dataset of the 2021 The Institute for Operations Research and the Management Sciences (INFORMS) Railway Applications Section (RAS) problem solving competition and won 2nd place. [ABSTRACT FROM AUTHOR]

In the present study, the mechanical properties and microstructure of C/Mullite composites with a PyC-SiC double-layer interfacial coating after annealing were systematically studied to evaluate the evolution of thermal stability in an inert atmosphere and a vacuum. The C/Mullite composites annealed in the inert atmosphere exhibited better thermal stability than those annealed under the vacuum. The main factor for failure of the composites was carbothermal reduction. The activation temperature of carbothermal reduction in composites in the inert atmosphere was ∼100 °C higher than that in the vacuum. Once carbothermal reduction was activated, the microstructure of composites was destroyed, resulting in a significant weight loss and mechanical property degeneration. The degeneration of mechanical properties was unrecoverable. [ABSTRACT FROM AUTHOR]

Continuous carbon fiber reinforced SiOC composites (C/SiOC) show promise for high-temperature application. Whereas, the high temperature resistances of SiOC ceramic matrix and carbon fiber are mismatched, which significantly restricts the long-term application of C/SiOC composites at high temperatures above 1250 °C. In this paper, heterogeneous element Y was introduced in C/SiOC composite by taking Y-doped MK resin as raw material to modify the structure of the SiOC ceramic matrix. Characteristics and high temperature evolution behaviors of SiYOC ceramic matrix in the inert environment were investigated. The microstructure, mechanical properties and high-temperature evolution of C/SiYOC composites were analyzed. The density, flexural strength and fracture toughness of the as-fabricated C/SiYOC composites were 1.89 g/cm3, 261.7 MPa and 13.54 MPa•m1/2, respectively. In the process of high-temperature treatment, the mechanical properties of C/SiYOC composites decreased obviously at 1500 °C due to the decomposition of SiYOC ceramics matrix and the carbothermal reductions between matrix and fibers. [ABSTRACT FROM AUTHOR]

The energy consumed by the heating, ventilation, and air conditioning (HVAC) system accounts for a large part of the energy consumption of buildings. Solar energy technologies in buildings have attracted more and more attention from scholars and architects because of their significant advantages in sustainable development, such as energy saving, environmental protection, and cost reduction. Sunspace has been studied for many years as a passive solar heating and ventilation technology. Nevertheless, there are also some problems associated with sunspace, such as overheating in summer and heat loss at night. The main objective of the work is to review the application of sunspace in buildings for heating and cooling, and possibly inspire more future works. This research adopts the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. The novelty of this work is to categorize different types of sunspaces according to the integration relationship with buildings and different configurations, materials and functions, and further analyze all the possible factors that can affect the performance of a sunspace. This paper concludes that sunspace can be divided into ventilated and unventilated sunspace based on the main utilization methods. According to their integration relationship with buildings, sunspace can also be divided into two types: façade and roof sunspace. Based on different configurations, materials and functions, façade sunspace further includes glazed sunspace, membrane sunspace, phase change material (PCM) sunspace; and roof sunspace includes on-top sunspace, courtyard sunspace, and integrated rooftop greenhouse. There are eight factors affecting sunspace performance that are further evaluated from the perspective of energy, environment, and economy. Directions of potential studies of sunspace are suggested. The authors hope that this research will be helpful to scholars and architects and promote the development of the multifunctional sunspace system. [ABSTRACT FROM AUTHOR]

Silicon oxycarbide (SiOC) ceramics has been prepared by polymethylsilsesquioxane (MK silicon resin) under inert environment at 1000 °C in the present work. The evolution behavior of compositions and structures of MK silicon resin derived SiOC ceramics at high temperatures in different environments were studied systematically. It was found that in inert environment, the rearrangement of Si–C and Si–O bonds took place at 1200 °C–1500 °C and the carobothermal reductions of SiOC ceramics were activated at 1500 °C. While in reduced pressure environment, lower pressure reduced the activation temperature of carbothermal reductions to 1400 °C. In air environment, partial Si[(O,C) 4 ] network oxidation and free carbon oxidation occurred at high temperatures, which would generate a large amount of SiO 2 and played a protective role in the interior of SiOC ceramics. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new intelligent temperature-controlled ventilated double-layer Trombe wall system for cold climate zones. This system consists of an insulation layer, an inner air channel, a massive wall, an outer air channel and a glazing plate. By changing the ventilated condition of inner and outer air layers, this system further contains three types of Trombe wall structures: inner ventilated (type 1), double ventilated (type 2) and outer ventilated (type 3). This system can automatically control the heat convection between rooms and Trombe walls, according to changes of air channel temperature that is affected by the local weather condition. Thereby, this system can avoid the problem of indoor heat loss at night and indoor overheating during the day. The main objectives of this paper are: 1) to compare the energy consumption of different types with the same thickness of inner and outer air layers; 2) to compare the thermal energy performance of the same type with different thickness of inner and outer air layers; and 3) to optimize the thickness of the inner and outer air layers of the three types of Trombe wall. Long-term experiments were conducted to investigate the heating potential of ventilated Trombe walls in Qingdao (cold climate zone), China. The thermal energy efficiency of three types of Trombe walls was compared and calculated using THERB for HAM software. The measured results demonstrated that the room temperature is always lower than the outer air channel temperature of the Trombe wall, and the heat of the Trombe wall is not fully utilized. Type 2 presents the best energy efficiency, followed by type 3 and type 1. For all types, when the outer air channel depth is greater than the inner air channel depth, the energy efficiency is improved. Affected by dry-bulb temperature and global horizontal irradiation, the monthly heating load of three types of Trombe walls in ascending order are April, November, March, February, December and January. Compared with a house without a ventilated Trombe wall, the heating efficiency of type 2, type 3 and type 1 is 32.6%, 30.5%, and 23.8%, respectively. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced mullite (C/Mullite) composites with favorable mechanical properties have been fabricated through sol-impregnation-drying-heating (SIDH) route in our previous work. For the further optimization of fabrication technology, it is very necessary to elucidate the evolution of microstructure and properties of C/Mullite composites during SIDH process. For this purpose, C/Mullite composites were fabricated at different cycles through SIDH route in present paper, and the effect of fabrication cycles on microstructure, mechanical properties and oxidation resistance of the composites were investigated. The results show that mullite matrix grew on the surface of single carbon fiber firstly, then grew from inside to outside of carbon fiber bundle during fabrication. Finally, it grew completely on the surface of the composites and formed a "mullite coating". Porosity of the composites decreased gradually and pores of the composites transformed from connected ones into isolated ones as the fabrication cycles increased. When the fabrication cycles reached 24, the porosity of the composites was unchanged basically. At the same time, the composites possessed the optimal mechanical properties and oxidation resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] Users' adaptive behaviors significantly affect the indoor environment and energy use. Neglecting them would introduce considerable uncertainty in the computer simulation results and lead to suboptimal or even invalid energy-efficiency solutions in optimization. To address this issue, we abstracted and simplified three user behavior patterns, including adjustment of operable shading devices, switching on/off artificial lighting, and opening windows for natural ventilation by a brief literature review. We then developed a new simulation approach that incorporates these behavior patterns and applied it to optimize the exterior fixed solar shade design of a south-facing office room in Qingdao as an example. The baseline model was established and validated in both daylight and energy simulations. The results demonstrate that the addition of user behavior models has a significant impact on both illuminance and load simulation results. The evaluation of each shading solution under the traditional approach and the newly-developed approach shows considerable differences, leading to the selection of different optimal solutions. Ultimately, the 0.6-meter-long type 8 (horizontal sunshade combined with vertical triangular panels on both sides) and 0.7-meter-long type 4 (double-sided vertical shading) were selected as the optimal solution using the traditional approach and new approach, respectively. This research offers valuable insights into the user behavior pattern and uses a shading optimization example to demonstrate the significant impact of incorporating adaptive behavior mechanisms on simulation and optimization results. The approach established in this paper has the potential to be extended to other solutions, being conducive to the study of refined building efficiency strategies for different conditions. [ABSTRACT FROM AUTHOR]

This study investigated the energy conservation of a non-insulated old apartment with a ventilated sunspace in Qingdao, China. The ventilation between the bedroom and sunspace of the apartment was controlled by the Delta temperature, which is equal to the sunspace temperature minus the bedroom temperature. EnergyPlus software was used to calculate the temperature, humidity, and thermal load of the apartment. The aim of this research is to analyze the sunspace performance at different flow rates and Delta temperatures. The flow rate between the sunspace and bedroom was set to range from 0.05 m3/s to 3 m3/s, and the Delta temperature was set to range from 0 to 2°C. It is found that when the ventilation between the sunspace and bedroom is activated under the condition that the Delta temperature is higher than 0.5°C, the heating load energy consumption decreases with increasing flow rate. When the flow rate is 0.3 m3/s and the Delta Temperature is 1.5°C in February, and the flow rate is 0.3 m3/s and the Delta temperature is 1°C in November, December, January, March, and April, the minimum energy consumption of the bedroom is 198.8 KWh/m2. Compared with bedroom without sunspace and with non-ventilated sunspace, Delta temperature-controlled ventilated sunspace can reduce the annual heating load energy consumption by nearly 14.7% and 4.4%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, Ni was introduced into the matrix of carbon fiber reinforced SiOC (C/SiOC) composites by the precursor infiltration and pyrolysis method to catalyze the generation of in situ formed nanostructures including carbon nanotubes (CNTs), turbostratic carbon, and SiC. The effect of in situ formed nanostructures catalyzed by Ni on the properties of the C/SiOC composites was investigated. The results demonstrated that the presence of in situ formed nanostructures in the matrix improved the densification and mechanical properties of C/SiOC composites. In addition, the incorporation of in situ formed nanostructures facilitated the formation of thermal conductivity pathways within the composites, thereby enhancing the thermal conductivity of C/SiOC composites. Furthermore, in situ formed nanostructures‐containing C/SiOC composites developed a carbon friction layer comprising CNTs and turbostratic carbon, which significantly enhanced the abrasion resistance, endowing C/SiOC composites stable friction coefficients, and lower levels of wear. [ABSTRACT FROM AUTHOR]

Three-dimensional carbon fiber preform reinforced mullite (C/Mullite) composites have been prepared through the sol-impregnation-drying-heating route in our previous studies. To further optimize the performance of C/Mullite composites, a PyC-SiC double-layer interfacial coating was introduced by polymer pyrolysis in this paper. The effects of PyC-SiC interfacial coating on the mechanical properties and thermal shock resistance of C/Mullite composites were investigated. It was found that the PyC-SiC interfacial coating played a positive role in protecting carbon fiber, weakening interfacial bonding and alleviating thermal mismatch between fiber and matrix. Consequently, both flexural strength and fracture work of C/Mullite composites were increased by more than 40%, and the thermal shock resistance in air was also improved. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the energy performance of an office building with a ventilated composite Trombe wall for winter heating application. The heating potential of composite Trombe wall for an office building was estimated using the dynamic thermal load calculation software, THERB for HAM. We designed a new composite Trombe wall which is oriented on the south side of the office building, and designed pipe with the fan that can control thermo-circulation, located in Kitakyushu, Fukuoka, Japan. The office building satisfies the Japan thermal regulation. The central concrete core of the wall is covered with a layer of dark paint, to improve absorptivity of the wall. In addition, to control air flow from the ventilated air layer to the indoor, the ventilation rates of the fan were controlled at 40 m3/h. The effects of those fans that is turned on and off at different time were also investigated. The temperature of the air layer of composite Trombe wall and the room is simulated. The investigation showed that the composite Trombe wall with optimized ventilation can reduce annual energy cost up to 3.7% compared to the composite Trombe wall without air supply. Highlights • Primary operating energy for heating during winter are minimized. • Comparative study on annual performance of a ventilated Trombe wall systems. • Composite Trombe wall have fan that help increase efficiency. • For building with the ventilated composite Trombe wall, the energy savings are round 3.7%. [ABSTRACT FROM AUTHOR]

Abstract Thermal shock behaviors of the carbon fiber needled felt reinforced sol-derived YAG (C/YAG) composites were investigated under static air at first. It is found that the preexistent cracks were enlarged and some new cracks were generated during thermal shock because of the obvious thermal expansion mismatch between carbon fiber and YAG. After thermal shock from 1200 °C or 1400 °C to room temperature for 10 times, mass losses of 3.64% and 2.75% are detected, respectively, due to the oxidation of carbon fibers. At the same time, the C/YAG composites retain only 34.7% and 30.8% of their original flexural strengths. After the infiltration of SiO 2 sol and its in-situ mullitization at 1300 °C, the cracks in surface layer of the C/YAG composites were well repaired, and the resistance to crack growth and propagation was strengthened. Accordingly, after the same thermal shock conditions, the mass losses are reduced to 0.64% and 0.85%, and the flexural strength retention ratios are increased to 66.7% and 60.2%. [ABSTRACT FROM AUTHOR]

Abstract The study concerning the second phase reinforced YAG matrix composites is few although YAG is well known as a desirable thermo structural ceramic. In this paper, low-cost 3D carbon fiber needled felt was used as reinforcement to improve the fracture toughness of YAG, and the carbon fiber needled felt reinforced YAG (C/YAG) composite was fabricated through vacuum impregnation-drying-heat treatment, using the Y 2 O 3 -Al 2 O 3 sol with a high solid content as raw material. The microstructure, mechanical properties, thermal stability and oxidation resistance of C/YAG composite were carefully investigated. Due to the characteristics of reinforcement and the microstructure, the as-fabricated C/YAG composite showed non-catastrophic failure behavior and much higher fracture toughness compared with monolithic YAG ceramic. The flexural strength of C/YAG composite was well retained after annealed at 1700 °C and 1800 °C under inert atmosphere. Although the chemical inertness between carbon fiber and YAG was confirmed up to 1800 °C, the physical bonding of interface was enhanced during annealing, which led to the decrease of fracture work, especially at 1800 °C. The oxidation resistance of C/YAG composite was related to the cracks and pores since YAG is immune to oxidation. The changes of microstructure and flexural strength after oxidation at 1200 °C, 1400 °C and 1600 °C were characterized and analyzed. Highlights • Low-cost 3D carbon fiber needled felt reinforced YAG composite is fabricated. • The fracture toughness of composite is twice more than that of monolithic YAG. • The composite shows favorable thermal stability and oxidation resistance. [ABSTRACT FROM AUTHOR]

Abstract By using Al-doped polysiloxane as raw materials, three-dimensional braided carbon fiber reinforced SiAlOC (C/SiAlOC) composites were prepared through precursor impregnation and pyrolysis route. The C/SiAlOC composites were further annealed at 1200 °C, 1300 °C, 1400 °C, 1500 °C and 1600 °C to investigate their thermal stability in inert atmosphere and vacuum, respectively. It is found that the C/SiAlOC composites keep stable up to 1500 °C in inert atmosphere and 1400 °C in vacuum, respectively. Owing to the enhanced thermal stability of SiAlOC ceramics compared with SiOC ceramics, the C/SiAlOC composites show superior thermal stability to the C/SiOC composites, especially in vacuum. [ABSTRACT FROM AUTHOR]

Ni-containing SiOC bulk ceramics have been prepared by spark plasma sintering at 1300 °C from polysiloxane at Ar atmosphere in the present work. The microstructure and properties of SiOC ceramics with different Ni content were studied. The resultant Ni-containing SiOC ceramics consists of in situ formed turbostractic layer carbon, CNTs (C nanotubes) and SiC crystals which dispersed in the SiOC matrix. With increasing content of Ni, the Ni-containing SiOC ceramics displayed less porosity. And the increasing Ni improved the mechanical, thermal and friction properties of SiOC ceramics. Ni-containing SiOC ceramics developed a carbon friction layer, which enhanced abrasion resistance to provide friction materials with stable friction coefficients and low abrasion values. A decrease in wear mass, from 2.06 to 0.18 mg was observed as the Ni content increasing from 0 to 2 wt%. The primary wear mechanisms of SiOC ceramics were recognized as abrasive wear, fatigue wear, and adhesion wear. [ABSTRACT FROM AUTHOR]

Ni-containing SiOC bulk ceramics have been prepared by spark plasma sintering at 1300 °C from polysiloxane at Ar atmosphere in the present work. The microstructure and properties of SiOC ceramics with different Ni content were studied. The resultant Ni-containing SiOC ceramics consists of in situ formed turbostractic layer carbon, CNTs (C nanotubes) and SiC crystals which dispersed in the SiOC matrix. With increasing content of Ni, the Ni-containing SiOC ceramics displayed less porosity. And the increasing Ni improved the mechanical, thermal and friction properties of SiOC ceramics. Ni-containing SiOC ceramics developed a carbon friction layer, which enhanced abrasion resistance to provide friction materials with stable friction coefficients and low abrasion values. A decrease in wear mass, from 2.06 to 0.18 mg was observed as the Ni content increasing from 0 to 2 wt%. The primary wear mechanisms of SiOC ceramics were recognized as abrasive wear, fatigue wear, and adhesion wear. [ABSTRACT FROM AUTHOR]

This paper presents a study on a mechanically ventilated Trombe wall that adds additional windows to the storage wall. The mechanically ventilated Trombe wall is located on the south side of the house with a central air conditioning and air circulation system. To reduce the heating load, during the heating period, the heat from the Trombe wall air channel is sent to the air conditioning room, from where it is then distributed and stored throughout the house by way of air circulation. Taking a house located in Miyazaki, Japan as an example, we conducted an actual survey to understand the situation of heat utilization of the Trombe wall and used numerical simulations to examine the effective method of heat utilization of the Trombe wall. Results showed that in all-day air conditioning, even when sending the air in the Trombe wall to the air-conditioned room, the temperature of the Trombe wall remained high. The heating load was reduced by sending the air from the Trombe wall to the central air-conditioned room and installing the large heat capacity material on the floor in the Trombe wall. [ABSTRACT FROM AUTHOR]

To improve fracture toughness of monolithic YAG ceramics, three-dimensional carbon fiber preform was employed as reinforcement, and the C/YAG composites without interfacial coating were fabricated through vacuum impregnation-drying-heat treatment route with an Y 2 O 3 -Al 2 O 3 sol as starting material. Characteristics and high-temperature evolution behaviors of the Y 2 O 3 -Al 2 O 3 sol with high solid content were analyzed. Then the microstructure and mechanical properties of C/YAG composites were characterized. The results indicate the Y 2 O 3 -Al 2 O 3 sol is an appropriate raw material for the fabrication of C/YAG composites. The C/YAG composites show a flexural strength of 294.6 MPa and a fracture toughness of 9.3 MPa m 1/2 although the total porosity reaches 13.8%. The flexural strength is comparable to the full dense monolithic YAG ceramics. The fracture toughness of monolithic YAG ceramic is remarkably enhanced due to the introduction of carbon fiber preform. The mechanical properties can be further improved if the porosity is reduced and the interfacial structure is optimized. [ABSTRACT FROM AUTHOR]

SiAlOC ceramics were fabricated by pyrolysis of Al-doped polymethyl(phenyl)siloxane at 1000 °C. Then SiAlOC ceramics were annealed under inert atmosphere at 1200 °C, 1400 °C, 1500 °C and 1600 °C, respectively, to investigate their high-temperature evolution behaviors. The transformations of microstructural units resulting from bonds redistribution are observed from 1000 °C to 1400 °C. Creation of mullite at 1400 °C and its crystallization at higher temperatures are confirmed. Carbothermal reaction is effectively suppressed due to low content of free carbon and formation of mullite in SiAlOC ceramics. Accordingly, enhanced thermal stability of SiOC ceramics is realized by incorporation of Al element. [ABSTRACT FROM AUTHOR]

To improve fracture toughness of monolithic Al 2 O 3 ceramics, three-dimensional carbon fiber preform was used as reinforcement, and the C/Al 2 O 3 composites without interfacial coating were fabricated through vacuum impregnation-drying-heat treatment route with an Al 2 O 3 sol as starting material. Characteristics of the Al 2 O 3 sol with high solid content were firstly analyzed. Then thermal stability and oxidation resistance of the C/Al 2 O 3 composites were investigated. It is found that the Al 2 O 3 sol is an appropriate raw material for the fabrication of C/Al 2 O 3 composites. The C/Al 2 O 3 composites with a total porosity of 15.5% show a flexural strength of 208.5 MPa and a fracture toughness of 8.1 MPa m 1/2 . Strength loss is observed after the composites were annealed at 1400 °C and 1600 °C under inert atmosphere. Oxidation resistance of the C/Al 2 O 3 composites is unsatisfactory because of the existence of open pores and microcracks. When Al 2 O 3 matrix was modified with SiO 2 , the oxidation resistance is remarkably improved due to the viscous flow effect of SiO 2 . [ABSTRACT FROM AUTHOR]

In this paper, we used a novel carbide (or ceramer) as the carbon precursor and studied the effect of etching temperature on its compositional and structural evolution in chlorine condition. The ceramer produced from a commercially available polymethyl(phenyl) siloxane resin at 600 °C under nitrogen still includes some organic groups (e.g., Si H, Si CH 3 , Si Ar), which cannot survive in chlorine for 3 h in range of 450–900 °C. The ceramer can be completely converted to carbon while the etching temperature exceeds 600 °C. Higher ordering at elevated etching temperatures and apparent increasing of mesopores at 600 °C were observed. [ABSTRACT FROM AUTHOR]

Microporous silicon carbide derived carbons (SiC-DCs) were obtained by chlorination with post treatment in ammonia (NH 3 ) using a commercially available polymethyl(phenyl)siloxane resin. In this paper, attentions were focused on the compositional and structural evolutions as well as the CO 2 capture performances of SiC-DCs as a function of chlorination temperature or affected by post-treatment. Microscopy analysis showed that the geometry and macrostructure, as well as the observed graphite ribbons were finely inherited from the as-received silicon carbide. Post-treatment under NH 3 could introduce a few nitrogen-contained groups to SiC-DCs, and has an advantage on increasing the ultra-microporosity with little effect on the carbon crystallinity, both of which finally help increasing the CO 2 adsorption capacity. Increasing etching temperature (900–1100 °C) would lead to a tiny increase of carbon crystallinity and porosity (specific surface area and total pore volume). However, the ultra-micropore volume decreased instead, thus leading to a decrease of CO 2 adsorption capacity. The final SiC-DCs samples exhibit excellent CO 2 capture performances at 0 °C under the ambient pressure, with a maximum value of 5.75 mmol/g. Under the same condition, the N 2 adsorption is as low as 0.46 mmol/g, suggesting a potential selective adsorbent for CO 2 and N 2 separation. [ABSTRACT FROM AUTHOR]

Microporous and mesoporous silicon oxycarbide derived carbons (SiOC-DCs) were obtained by chlorination with post treatment in ammonia (NH 3 ) using a commercially available polymethyl(phenyl)siloxane resin. In this paper, attentions were focused on the structural evolution and electrochemical performance of SiOC-DCs as a function of pyrolysis temperature. Results showed that the geometry and macrostructure of SiOC-DCs, as well as the carbon ribbons were finely inherited from SiOC. The SiOC-DCs porosity and crystallinity depends mainly on the pyrolysis temperature. Post treatment by NH 3 could further increase the sample porosity, and had little affection on the carbon crystallinity. The final SiOC-DCs samples exhibit excellent electrochemical performance as electrodes for supercapacitors, with a relatively high specific capacitance value up to 148.7 F g −1 and good capacitance retention ratio up to 94.3% after 2000 charge–discharge cycles at a current density of 1 A g −1 with KOH aqueous solutions as electrolyte. Increasing pyrolysis temperature would lead to a continual decline of specific capacitance. [ABSTRACT FROM AUTHOR]

The 3D carbon fiber-reinforced mullite matrix (3D-Cf/mullite) composites were fabricated via sol–gel process, using mullite sols with high solid content as precursor. The mullitizaiton process of mullite sols was investigated with XRD and TEM. The results showed that the sol was transformed into orthorhombic mullite at 1300°C with a trace of amorphous SiO2 between crystals of mullite. The flexural strength, fracture toughness and interlaminar shear strength of 3D-Cf/mullite composites were 277.6MPa, 12.3MPam1/2 and 36.3MPa, respectively. The 3D-Cf/mullite composites exhibited a significant tough fracture behavior. The oxidation resistance of 3D-Cf/mullite composites was examined. It can be found that the strength retentions of 3D-Cf/mullite composites were 62.9%, 84.8% and 13.6% after oxidation at 1300°C, 1500°C and 1700°C, respectively. The strength transformation was interpreted with the microstructure analysis of oxidized 3D-Cf/mullite composites at different temperatures. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous silicon oxycarbide ceramics without free carbon were prepared by pyrolysis of cross-linked polysiloxane at different temperatures (1300–1450°C) followed by post treatments. The post treatments comprised two steps (HF etching and oxidation at 650°C in air). The sample pyrolyzed at 1300°C after post treatments exhibits the largest specific surface area (SSA) reaching up to 204m2/g and the biggest total pore volume (0.58cm3/g) with an average pore size of 11.4nm. Increasing pyrolysis temperature will lead a quick decline of SSA and total pore volume. The thermal stability of pore structure of the sample pyrolyzed at 1300°C with post treatments was investigated in air. The SSA and total pore volume almost keeps the same up to 750°C, and subsequently decreases with a high speed. The most possible reason is the pores are severely closed by viscous flow of SiO2 produced from SiC nanocrystallites. [Copyright &y& Elsevier]

Abstract: Homogeneous silicon oxycarbide (SiOC) ceramic powders were prepared by pyrolysis of cross-linked polysiloxane at different temperatures (1250–1500°C) under vacuum. The effect of pyrolysis temperature on the pore structure evolution was investigated by means of N2 adsorption, SEM, XRD, IR and element analysis (EA). Studies showed that predominate mesoporous ceramics with the average pore size in the range of 2–13nm were obtained after pyrolysis in this temperature range. The pore structure transformation is strongly correlated with the thermolytic decomposition process of the used precursor, such as phase separation and carbothermal reduction. At relatively lower temperature (1250–1350°C), the ceramics had a relative small specific surface areas (35m2/g) owing to the low degree of carbothermal reduction. However, as the carbothermal degree had an obvious augment at relative higher temperature (1400–1450°C), the specific surface areas and total pore volume increased and reached to the maximum of 66m2/g and 0.214cm3/g, respectively, and subsequently decreased rapidly after 1500°C for the reason of partial sintering of the nano-sized SiC derived from polysiloxane. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) carbon fiber reinforced silicon oxycarbide (Cf/SiOC) composites were fabricated through precursor impregnation and pyrolysis process using siloxane resin as precursor. These composites were further annealed at various temperatures to follow their mechanical properties and microstructure evolutions in reduced pressure environment. The decrease in strength of those composites could be attributed mainly to the decomposition of matrixes. When the annealing temperature increased from 1000 to 1250°C, the mechanical properties of composites did not change too much, despite the matrixes underwent a redistribution of Si–O bonds and Si–C bonds. At temperature above 1300°C, due to the weight loss and volume shrinkage of matrixes caused by carbothermal reduction, both the flexural strength and elastic modulus of Cf/SiOC composites decreased rapidly. [Copyright &y& Elsevier]

Abstract: Three-dimensional carbon fiber reinforced silicon oxycarbide (3D Cf/SiOC) composites were fabricated through precursor infiltration and pyrolysis processing (PIP) using siloxane resin as precursor. These composites were further annealed at various temperatures to investigate their microstructure and mechanical property evolutions. It was found that the annealing temperature played a crucial role on the microstructure and mechanical properties of Cf/SiOC composites. When the annealing temperature increased from 1200 to 1400°C, the mechanical properties of composites did not change too much, despite the matrixes underwent a redistribution of Si–O bonds and Si–C bonds. At temperature above 1500°C, both the flexural strength and modulus decreased rapidly. This behavior was directly related to the weight loss and volume shrinkage of matrixes caused by carbothermal reductions occurred in matrixes. [Copyright &y& Elsevier]

Abstract: Silicon oxycarbide glasses (SiOC) have been produced by siloxane resin under flowing argon at 1000°C and then their evolutions in air from 800 to 1700°C were investigated. Those glasses annealed at various temperatures were characterized by X-ray diffraction, 29Si MAS NMR, Raman spectroscopy, and chemical element analysis. It can be found that oxidation reactions of the SiOC glasses occurred at above 1000°C; carbothermal reduction was indiscernible at temperature below 1600°C but almost finished at 1700°C; and the decomposition of SiO x C4−x network was complete at 1400°C. [Copyright &y& Elsevier]

Abstract: Silicon oxycarbide glasses (SiOC) have been produced by siloxane resin under flowing argon atmosphere at 1000°C. Those glasses were further annealed at 1200, 1300, 1400, and 1500°C under the pressure of 0.01KPa and 101KPa, respectively, to investigate the effect of environment pressure on their high temperature stability. The two series of glasses were characterized by X-ray diffraction, 29 SiMASNMR, and chemical element analysis. The environment pressure plays a crucial role on high temperature stability of SiOC glasses by promoting or hindering bonds redistribution and carbothermal reductions. It can be found that SiOC glasses exhibit enhanced thermal stability in high pressure environment. [Copyright &y& Elsevier]

Miscible and near-miscible flooding are used to improve the performance of carbon-dioxide-enhanced oil recovery in heterogeneous porous media. However, knowledge of the effects of heterogeneous pore structure on CO2/oil flow behavior under these two flooding conditions is insufficient. In this study, we construct pore-scale CO2/oil flooding models for various flooding methods and comparatively analyze CO2/oil flow behavior and oil recovery efficiency in heterogeneous porous media. The simulation results indicate that compared to immiscible flooding, near-miscible flooding can increase the CO2 sweep area to some extent, but it is still inefficient to displace oil in small pore throats. For miscible flooding, although CO2 still preferentially displaces oil through big throats, it may subsequently invade small pore throats. In order to substantially increase oil recovery efficiency, miscible flooding is the priority choice; however, the increase of CO2 diffusivity has little effect on oil recovery enhancement. For immiscible and near-miscible flooding, CO2 injection velocity needs to be optimized. High CO2 injection velocity can speed up the oil recovery process while maintaining equivalent oil recovery efficiency for immiscible flooding, and low CO2 injection velocity may be beneficial to further enhancing oil recovery efficiency under near-miscible conditions. [ABSTRACT FROM AUTHOR]

SiHfOC ceramics with different Hf contents were prepared by the sol-gel method using polymethylsilsesquioxane and HfOCl 2 ·8H 2 O as the raw materials. The high-temperature structural evolution of the SiHfOC ceramics with different Hf contents was investigated under an inert atmosphere. The results showed that Hf existed in the free state in the SiHfOC precursors with Hf:Si atomic ratios of 0.05 and 0.1. When the Hf:Si ratio was increased to 0.2, Hf was bridged in the SiOC network to form Si–O–Hf bonds, which changed the pyrolysis behavior of the ceramics and improved the ceramic yield. Further, the formation of Si–O–Hf bonds promoted the uniform dispersion of HfO 2 nanocrystals inside the ceramic, which further inhibited carbothermal reduction and increased the thermal stability of the SiHfOC ceramics. [ABSTRACT FROM AUTHOR]

Earth-air heat exchanger (EAHE) is a passive technique that can reduce the energy consumption for indoor heating and cooling. This paper aims to evaluate the performance of EAHE in Qingdao, China by using a proposed all-in-one simulation model according to the parametric performance design method. This model can predict the performance and feasibility of EAHE and generate various required results with just one click. It was also validified by the actual field experiment to prove its appropriateness. In the simulation, the influence of eight parameters on the outlet air temperature was firstly analyzed to understand their interrelationships. Secondly, thermal capacity and heat transfer efficiency were evaluated to test the performance of EAHE. Finally, this paper provided a feasibility analysis of EAHE. The findings indicate that deeper burial depth, longer tube length, and smaller tube diameter can achieve better heat transfer efficiency and thermal capacity. However, when tube length exceeded 40 m, burial depth exceeded 2 m, or tube conductivity was higher than 1W/m-K, the change in the outlet air temperature was no longer substantial. More importantly, the feasibility analysis suggested a promising application prospect for EAHE in Qingdao. The maximum average daily cooling and heating capacities of the system were 15.56 kW and 18.49 kW, respectively. The maximum heat transfer efficiency of the system in July (86.02%) and January (87.89%) can be obtained, when the tube length was 70 m and the inlet airflow speed was 1 m/s, respectively. The economic feasibility analysis indicated that EAHE could save 507.8 Yuan each year, and the payback period was about 6.2 years. [ABSTRACT FROM AUTHOR]

Abstract: An Al-doped SiAlOC polymer was derived from polymethyl(phenyl)siloxane resin and aluminum tri-sec-butoxide through sol–gel preparation. After dried, this polymer was further annealed at 400, 600, 800 and 1000°C in inert atmosphere to follow its structural evolution. These pyrolyzates obtained at various temperatures were characterized by thermogravimetric analysis (TGA), elemental analysis (EA), 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR). It can be found that the conversion of the polymer into an inorganic network is achieved at 1000°C. There are at least seven different Si and two different Al units in SiAlOC polymer. In the mineralization process from polymer to glass, two different Si units remained at the inorganic network and the transition from AlO6 to AlO4 occurred. [Copyright &y& Elsevier]

Abstract: Silicon oxycarbide (SiOC) and aluminum-containing silicon oxycarbide (SiAlOC) glasses were obtained through pyrolysis in argon atmosphere at 1000°C of a polymethyl(phenyl)siloxane resin and aluminum tri-sec-butoxide-derived siloxane networks. These glasses were further annealed at 1200, 1300, and 1400°C in vacuum atmosphere to investigate their high-temperature behavior. The two types of glasses were characterized by X-ray diffraction, 29SiMASNMR, 27AlMASNMR, and chemical element analysis. The aluminum incorporated into structure plays a major role on the thermal stability of SiOC by hindering carbothermal reductions. It can be found that introducing aluminum into structure should be an effective way to enhance the thermal stability of SiOC glasses. [ABSTRACT FROM AUTHOR]

The Si 3 N 4 raw powder, sintering aids, and sintering process are the most critical factors affecting the thermal conductivity and mechanical properties of Si 3 N 4 ceramics. The impact of sintering aids content and powder characteristics on gas pressure sintered Si 3 N 4 ceramics was investigated in this study. Lower aids content facilitated phase transformation prior to densification, promoting a pronounced bimodal microstructure. Based on in-situ shrinkage behavior, liquid phase sintering of Si 3 N 4 ceramics can be divided into three stages without clear boundaries. Between 1200 and 1400 °C, higher oxygen and metallic impurities favored particle rearrangement. Between 1400 and 1800 °C, the dissolution and precipitation process was probably controlled by the α-phase ratio and particle size. Above 1800 °C, subsequent grain growth was primarily facilitated by the Ostwald ripening process, leading to a reduced densification rate. Higher oxygen content leading to greater weight loss during sintering. Higher Fe resulted in a darker color of sintered Si 3 N 4 ceramics. High α-phase content promoted the formation of a bimodal microstructure and ensured superior mechanical properties. Reduced levels of oxygen and aluminum were prerequisites for achieving high thermal conductivity. Powders prepared by silicon nitriding method were cost-effective materials for the preparation of high-performance Si 3 N 4 ceramic substrates. [ABSTRACT FROM AUTHOR]

The SiC/SiBCN composites were prepared via polymer infiltration and pyrolysis (PIP) technique. The structural composition and property evolution behavior of the composites under inert high-temperature environment were investigated to reveal the failure mechanism of the composites. With the increase of the heat treatment temperature from 1500 °C to 1600 °C, the composite properties underwent a sharp decline. Among them, the weight loss rate gradually increased from 3% to 9% and the density decreased from 2.4 g/cm3 to 2.3 g/cm3. Especially, the room temperature flexural strength decreased from 267 ± 7 MPa to 179 ± 3 MPa and the strength retention were 46%. The degradation of SiC fiber properties is the main factor for the decrease in flexural strength of the composites at below 1500 °C. When heat treatment temperature above 1600 °C, the mechanical properties of SiC fiber dramatically decline, and the SiBCN ceramic matrix initially precipitated Si 3 N 4 crystalline phase leading to a carbothermal reduction reaction. Hence, the mechanical properties of the composite at T > 1600 °C deteriorate sharply under the influences of the above two negative factors. [ABSTRACT FROM AUTHOR]

Polymer-derived Silicon oxycarbide (SiOC) and yttrium-containing silicon oxycarbide (SiYOC) ceramics were obtained in the present work. To investigate their high temperature behaviors in low pressure atmosphere, these ceramics were further annealed at 1200 °C, 1300 °C, 1400 °C, and 1500 °C. The structure evolutions of SiOC and SiYOC ceramics through heat-treatment were studied. It was found that the carbothermal reductions of SiOC ceramics were activated at 1400 °C and almost finished at 1500 °C. The introduction of Y element played a major role on high temperature stability by influencing the structure evolution of SiOC and hindering the carbothermal reductions. The results show that introducing yttrium to modify the SiOC structure should be an effective way to enhance the thermal stability of SiOC ceramics. [ABSTRACT FROM AUTHOR]

Alumina matrix composites reinforced with the laminated and stitched carbon fibre cloth preform were fabricated through the infiltration-drying-heating route using the Al2O3 sol with a high solid content as raw materials. The investigation was focussed on the characteristics of sol and the mechanical properties and high-temperature resistance of C/Al2O3 composites. α-Al2O3 with favourable sintering activity can be obtained after heat treatment of sol at 1200∘C. The as-received C/Al2O3 composites with a total porosity of 16.8% exhibit a flexural strength of 271.3 MPa and a notch toughness of 13.0 MPa m1/2, respectively. As a result of the evolution of interface and matrix, the flexural strength of C/Al2O3 composites is decreased by 28.5% after heat treatment at 1600∘C for 1 h under inert atmosphere. At the same time, fracture mode of composites is transformed from tough to brittle behaviour. [ABSTRACT FROM AUTHOR]

Based on numerical simulations, the heating load reduction effect of an attached sunspace in winter was determined, and the effective heat utilization method and sunspace design were explored. In this paper, we studied the heating load reduction effect using heat from the sunspace and temperature fluctuation of each room at the time of heat use from the sunspace (sending air from the sunspace to the heating, ventilation, and air conditioning (HVAC) machine room and taking the air to the adjacent rooms). In the case of the all-day HVAC system, it was confirmed that a larger capacity of sunspace and not sending air from the sunspace to the adjacent room demonstrated a better heating-load reduction effect. Compared with Model Iw (a house with a window on the exterior of the sunspace opened to external air), Model I (a house with an attached sunspace on the second floor) could save approximately 41% of the total energy. Model II (a house with the attached sunspace both on the first and second floors) could save approximately 84% of the total energy. Sending heat from the sunspace to the adjacent room led to temperature increases in the adjacent rooms. However, if the construction plan is to have the sunspace only on the second floor, the house should be carefully designed, for example, by placing a living room on the second floor. [ABSTRACT FROM AUTHOR]

Molecular simulations are currently receiving significant attention for their ability to offer a microscopic perspective that explains macroscopic phenomena. An essential aspect is the accurate characterization of molecular structural parameters and the development of realistic numerical models. This study investigates the surface morphology and elemental distribution of silicon nitride fibers through TEM and EDS, and SEM and EDS analyses. Utilizing a customized molecular dynamics approach, molecular models of amorphous and multi-interface silicon nitride fibers with complex structures were constructed. Tensile simulations were conducted to explore correlations between performance and molecular structural composition. The results demonstrate successful construction of molecular models with amorphous, amorphous–crystalline interface, and mixed crystalline structures. Mechanical property characterization reveal the following findings: (1) The nonuniform and irregular amorphous structure causes stress concentration and crack formation under applied stress. Increased density enhances material strength but leads to higher crack sensitivity. (2) Incorporating a crystalline reinforcement phase without interfacial crosslinking increases free volume and relative tensile strength, improving toughness and reducing crack susceptibility. (3) Crosslinked interfaces effectively enhance load transfer in transitional regions, strengthening the material's tensile strength, while increased density simultaneously reduces crack propagation. [ABSTRACT FROM AUTHOR]

Recently, Jakarta has implemented a new standard for new building construction to reduce the energy consumption of office buildings. This has to meet the minimum overall thermal transfer value (OTTV) of 35 watt/m2. In tropical countries, the most effective passive design strategy method is the use of shading devices. Dense shading will more effectively reduce energy consumption but will reduce visibility through the opening. Sudare is a traditional Japanese blind made from bamboo.Its original function was to prevent direct solar radiation and introduce natural ventilation. The characteristic Sudare form makes it possible to see through to objects outside the house. The aim of this research is to identify an alternate mode of façade configuration using external horizontal blinds based on the Sudare form to meet the minimum standard of Indonesian National Standard (SNI), with greater efficiency in terms of thermal energy use to minimize energy consumption and maintain visual comfort. Ladybug and Honeybee inside the Grasshopper plugin of Rhinoceros 3D with the Energy plus engine will be used to simulate a standard building as baseline performance, and buildings that use different Sudare dimensions and spacers as shading devices parametrically. Based on this study, the optimum form of Sudare blind, with a diameter of 10.01 mm and 5 mm spacers, has achieved a 5% reduction in OTTV and a 6% reduction in thermal energy use, as compared to the baseline building. It also gives better uniformity of daylight distribution, which improves visual performance and comfort. [ABSTRACT FROM PUBLISHER]

Polymer-derived SiBCN ceramics are well known for their outstanding thermal stability. Although they possess outstanding thermal stability, SiBCN ceramics are easily to decompose out Si3N4 and SiC crystalline phases at high temperature leading to thermal stability worsen. Here, to reduce the Si3N4 crystallization precipitation in SiBCN ceramics, the N contents are reduced from 25 to 8.09 wt%, 11.44 and 14.51 wt%, by adding polycarbosilane into polyborosilazane, respectively. The experimental results illustrated that the precipitation temperature of Si3N4 phase in modified S1–S3 ceramics increased to 1800 °C which was higher than that of S0 ceramics (1600 °C). The results indicated that the crystalline precipitation of Si3N4 in SiBCN ceramics can be suppressed at a high-temperature environment via declining N content, which may provide a new strategy for decreasing carbothermal reduction. In addition, the original SiBCN ceramic had a weight change of 31.7% at T > 1800 °C, while the weight change of modified SiBCN ceramics significantly reduced to 15.7 ~ 19.5%, which attributed to the decrease in carbothermal reduction. [ABSTRACT FROM AUTHOR]

In this work, a novel ceramic precursor containing boron, silicon, and nitrides (named SiBCN) was synthesized from liquid ceramic precursors. Additionally, its pyrolysis, microstructure, and chemical composition were studied at 1600 °C. The results showed that the samples with different boron contents had similar structural composition, and both of the two precursors had stable amorphous SiBN structures at 1400 °C, which were mainly composed of B-N and Si-N and endowed them with excellent thermo-oxidative stability. With the progress of the heating process, the boron contents increased and the structures became more amorphous, significantly improving the thermal stability of the samples in high-temperature environments. However, during the moisture treatment, the introduction of more boron led to worse moisture stability. [ABSTRACT FROM AUTHOR]

Trombe wall technology, a passive solar design strategy, has garnered significant interest for its potential to reduce building energy consumption. This paper presents a comprehensive review of the evaluation and optimization trends for Trombe walls. The historical evolution and recent advancements in Trombe wall systems are critically analyzed. Furthermore, key optimizing parameters are discussed in detail, including material selection, wall thickness, insulation characteristics, window specifications, vent dimensions, and intelligent control strategies. Common experimental methodologies and simulation approaches employed for Trombe wall optimization are summarized. Finally, current research limitations are identified and future research directions are proposed to fill existing knowledge gaps and facilitate the widespread adoption of optimized Trombe wall systems for improved energy efficiency in buildings. • One figure shows the timeline of Trombe wall development. • Subdivided statistical analysis of Trombe wall research trends in the past five years. • Rich and detailed original Trombe wall diagram. [ABSTRACT FROM AUTHOR]

• The constructed cores mimic five kinds of possible heterogeneities of a real core. • Petrophysical heterogeneity is well correlated to nonuniform porosity distribution. • Effect of 3D heterogeneity with measured local property on coreflooding is tested. • Response of S CO2 distribution to 1D, 2D and 3D inhomogeneity is analyzed. • Model deviation by errors setting heterogeneous structure in 3D core is quantified. Core heterogeneity is an important factor influencing CO 2 and brine migration in porous media but difficult to be accurately described using models. In this study, we quantitatively evaluate the effects of the errors between core heterogeneity and the simplified models on numerical modeling of CO 2 core flooding. Results indicate: 1) The model error from the 1D simplification of 3D petrophysical heterogeneity could make the multiphase flow modeling fail to reflect the mean behavior of the core plug, and the resultant deviations in the averaged CO 2 saturation (S CO2) can span from -0.1 to 0.2. Besides, using the 1D heterogeneous core model in the modeling generally conceals the local S CO2 buildup and accordingly clouds judgment about variation trend of the local S CO2. 2) The settings of the local petrophysical properties for the low-porosity heterogeneous structures in the cores have a significant impact on the predicted S CO2 distribution in front of these structures. Particularly, the errors in their capillary entry pressure could lead to the significant underestimation of the local S CO2 near them. Consequently, the model outputs cannot reflect the local S CO2 buildup behavior. 3) Both magnitude and variation trend of the predicted local S CO2 could be numerically sensitive to 3D heterogeneity distribution, notably increasing the probability of the mismatching between model predictions and experimental observations. Comparatively, more efforts should be paid to the parameter setting of the heterogeneous structures in order to improve the reliability of the CO 2 core flooding modeling. [ABSTRACT FROM AUTHOR]

Highlights • A LB Model for hydrate formation is constructed and applied to an experiment. • It considers the effects of salts on mass transfer and hydrate formation kinetics. • The predicted water conversion can match well with experimental measurement. • It applies to analyze hydrate formation mechanism and desalination efficiency. Abstract In this study, we develop a numerical model based on Lattice Boltzmann (LB) method for simulating hydrate formation in brine, aiming at bridging the gap between microscopic mechanism and macroscopic experimental observations. The model employs convection-diffusion equations, coupled with salt exclusion and salinity-dependent hydrate formation kinetics, and is applied into an experiment of cyclopentane-hydrate formation in brine. Numerical simulation results indicate: 1) the predicted water conversion under wide salinity conditions can match well with experimental measurement and their deviations are less than 9%, much lower than the measurement error; 2) the salt exclusion by hydrate formation decreases the concentration of guest molecule and lowers the hydrate formation rate. The rapidly increased hydrate surface area offsets such effects of the enhanced salt concentration and promotes the rapid formation of the hydrate at the initial stage. Then, the constantly decreased concentration of guest molecule and enhanced concentration of the salt ions dominate the hydrate formation rate and gradually slow down the hydrate formation process; 3) the hydrate morphology significantly depends on guest molecule diffusion length. Comparatively, the effect of salinity on it is small and can be reasonably ignored. This LB model could have a potential application for analyzing the formation mechanism of oceanic hydrate and predicting the efficiency of hydrate-based desalination. [ABSTRACT FROM AUTHOR]

Abstract: The wettability of V-active PdCo-based alloys on Si3N4 ceramic was studied with the sessile drop method. And the alloy of Pd50.0–Co33.7–Ni4.0–Si2.0–B0.7–V9.6 (wt%), was developed for Si3N4 ceramic joining in the present investigation. The rapidly-solidified brazing foils were fabricated by the alloy Pd50.0–Co33.7–Ni4.0–Si2.0–B0.7–V9.6. The average room-temperature three-point bend strength of the Si3N4/Si3N4 joints brazed at 1453K for 10min was 205.6MPa, and the newly developed braze gives joint strengths of 210.9MPa, 206.6MPa and 80.2MPa at high temperatures of 973K, 1073K and 1173K respectively. The interfacial reaction products in the Si3N4/Si3N4 joint brazed at 1453K for 10min were identified to be VN and Pd2Si by XRD analysis. Based on the XEDS analysis result, the residual brazing alloy existing at the central part of the joint was verified as Co-rich phases, in which the concentration of element Pd was high up to 18.0–19.1at%. The mechanism of the interfacial reactions was discussed. Pd should be a good choice as useful alloying element in newer high-temperature braze candidates for the joining of Si-based ceramics. [Copyright &y& Elsevier]

Abstract: SiC fiber reinforced SiC matrix (SiCf/SiC) composites, employing two types of KD SiC fibers (from National University of Defense Technology, China) with different fiber surface characteristics as reinforcements, were fabricated by precursor infiltration and pyrolysis (PIP) process. The fiber surface characteristics were evaluated by SEM, XPS and Raman analysis. The effects of fiber surface characteristics on the interfacial microstructure and mechanical properties of the KD SiCf/SiC composites were investigated. The results show that the tensile strength of the KD-2 SiC fibers (with silicon-based oxide surface layers) is about 85% that of the KD-1 SiC fibers (with pyrocarbon (PyC) surface layers), but the flexural strength of the KD-2 SiCf/SiC composite is only around 15% that of the KD-1 SiCf/SiC composite. SEM, TEM and elemental mapping analysis show that the large strength difference between the two composites is ascribed to the interfacial microstructure and the degree of fiber damage, which are arising from the different fiber surface characteristics. [Copyright &y& Elsevier]