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The enhanced performance of aerospace equipment drives parts development towards integration, complexity, and structural optimization. This advancement promotes metal near-net fabrication technologies like wire electrical discharge machining (WEDM) and 3D printing. However, the high initial surface roughness from WEDM or 3D printing poses significant challenges for the high-performance surface finishing required. To effectively reduce the surface roughness of the workpieces with high initial surface roughness, this paper proposes pulsed unipolar-polarisation plasma electrolytic polishing (PUP-PEP). The study examined the material removal mechanisms and surface polishing quality of PUP-PEP. This technique combines the high current density and material removal rate of the electrolytic polishing mode with the superior surface polishing quality of PEP through voltage waveform modulation. For an Inconel-718 superalloy part fabricated by WEDM, PUP-PEP reduced surface roughness from Ra 7.39 μm to Ra 0.27 μm in 6 min under optimal conditions. The roughness decreased from Ra 7.39 μm to Ra 0.78 μm in the first 3 min under pulsed unipolar-polarisation voltage, resulting in a remarkable 233% increase in efficiency compared to that with conventional PEP. Subsequently, the voltage output voltage is transformed into a constant voltage mode, and PEP is continued based on PUP-PEP to finally reduce the workpiece surface roughness value to Ra 0.27 μm. The proposed PUP-PEP technology marks the implementation of 'polishing' instead of conventional rough-finish machining processes, presenting a new approach to the surface post-processing of metal near-net fabrication technologies. [ABSTRACT FROM AUTHOR]

Zirconia is gradually used in manufacturing aerospace and other fields because of its excellent mechanical processing properties. Due to its hardness and brittleness, zirconia can easily cause excessive and unstable changes in grinding force during machining, resulting in extensive surface damage and poor surface quality. Therefore, it is important to establish an appropriate grinding force model and achieve accurate control and prediction of the grinding force. Ultrasonic-assisted grinding can reduce grinding forces, improve workpiece surface quality, and increase processing efficiency. However, the grinding force model for ultrasonic-assisted grinding is still not adequately investigated. In this study, a new method for predicting the axial force of ultrasonic-assisted grinding is proposed. Vickers hardness and indentation fracture theories combine two different methods: plastic removal and brittle fracture. Moreover, conventional and ultrasonic-assisted grinding tests are performed. Then, the relationship between grinding forces and process parameters is investigated using numerical statistical calculation methods. The grinding force data obtained from the test validate the theoretical model, with the average error between the theoretical and experimental values being 22.87%. The influence of machining variables on the grinding force is investigated, and experimental results of conventional al grinding and ultrasonic-assisted grinding are compared. It is found that the rotary ultrasonic-assisted grinding force can be reduced by up to 66.76%. [ABSTRACT FROM AUTHOR]

To investigate the impact of various forms of hole expansion strengthening of split mandrel (HESSM) process on the fatigue performance of 7050 aluminum alloy, a 3D finite element simulation analysis model is established for once hole expansion strengthening (OHES) and twice hole expansion strengthening. HESSM experiment is conducted to explore its influence on hole wall stress, microstructure, and fatigue life. The results show that the depth of the plastic deformation layer in the middle area of the hole wall is 1.69 times for specimens by twice hole expansion strengthening than that of OHES. Additionally, residual stress on the hole wall is higher and uniform for compared with OHES, when by twice hole expansion strengthening in opposite directions (THESOD) using split mandrel. The median fatigue life of the specimen by OHES is 1.52 times that of without expansion strengthening (WES). The median fatigue life of the specimen by twice hole expansion strengthening in the same direction using split mandrel is 1.73 times that of WES, and the median fatigue life of the specimen by THESOD using split mandrel is 1.80 times that of WES. [ABSTRACT FROM AUTHOR]

To improve the fatigue performance of 7050 aluminum alloy specimen with holes, the anti-fatigue strengthening mechanism of the process with ultrasonic vibration–assisted hole expansion strengthening (UVAHES) is investigated. The experiment of UVAHES 7050 aluminum alloy is performed, and the effects of ultrasonic vibration on the residual stress, surface roughness (Sa) and surface morphology of the hole wall of the specimen are studied, and the fatigue life and fracture morphology of the specimen are compared. The results show that the maximum residual compressive stress of the hole wall of UVAHES specimen is greater than that without ultrasonic hole expansion strengthening (WUHES). After the specimen is loaded, the hole wall stress is negatively correlated with the residual compressive stress, resulting in the maximum stress of the hole wall of UVAHES specimen is less than that of WUHES. The Sa of the hole wall of UVAHES specimen is 0.946 μm, which is less than that of WUHES and the without expansion strengthening (WES). The median fatigue life of UVAHES specimen is 1.5 times that of WES, and the median fatigue life of WUHES specimen is 1.2 times that of WES. The process of UVAHES, the number of times that the mandrel expansion strengthening the hole wall increases, the surface morphology of the hole wall improves, the residual compressive stress of the hole wall increases, thereby improving the fatigue performance of the specimen. [ABSTRACT FROM AUTHOR]

SiCf/SiC composites have promising applications in aerospace industries. SiCf/SiC composite micro-holes are important components, such as gas film holes on turbine blades. However, micro-hole machining in the SiCf/SiC composite is challenging because of its excellent mechanical and physical properties and poor machinability caused by micro-hole constraints. Therefore, a novel brazed diamond abrasive core drill was designed to achieve high self-sharpness by continuously losing blunt diamond grits and exposing sharp diamond grits. The wear and self-sharpness of the developed drill were investigated and compared with those of an electroplated diamond core drill during ultrasonic vibration-assisted drilling of SiCf/SiC composite micro-holes. The material removal behaviors of SiCf/SiC composites, including drilling forces, exit tearing, hole dimensions, hole wall quality, and the wear of core drills, were also studied. The developed core drill demonstrated reduced drilling force and a significantly prolonged lifetime. Further, it achieved superior drilling performance, drilling accuracy, and micro-hole quality. [ABSTRACT FROM AUTHOR]

Grinding force has an important impact on the ground precision and quality of a workpiece. At present, the effects of the workpiece structure and the change in the abrasive wheel diameter on grinding force are ignored during profile grinding. Therefore, to reduce the grinding force and improve the grinding integrity, profile grinding experiments were conducted on the structure of FGH96 turbine disc slots (TDS) using an electroplated cubic boron nitride (CBN) abrasive wheel. The built grinding force model was evaluated. The influences of the grinding parameters on the grinding force were determined through absolute sensitivity analysis. In addition, the grinding force affected by the slot structure was also studied. Results show that the average errors of the radial and tangential profile grinding forces were 12.8% and 13.4%, and the standard deviation of errors were 5.4% and 5.9%, respectively. The absolute sensitivity of the profile grinding force to the workpiece infeed speed and the depth of cut was positive and that to the abrasive wheel speed and diameter was negative. Furthermore, the grinding forces varied at different positions of slots ground surface. According to the standard deviation, the larger grinding parameters is, the larger dispersion degree of the grinding force will be. The results could provide significant guidance for parameter selection or optimization. [ABSTRACT FROM AUTHOR]

Plasma electrolytic polishing (PEP) is an innovative technology used in polishing metal workpiece surfaces, especially for complex workpieces. To date, the function of the vapour gaseous envelope (VGE) fluctuation in electrolyte plasma polishing remains indistinct, leading to differences in understanding of the smoothing mechanism of PEP. This paper primarily aims to reveal the evolution process of VGE with voltage change and the function mechanism in the PEP. Accordingly, the polishing efficiency, change of electrolyte properties, and electrical signal data of stainless steel are experimentally investigated under different voltages. The results show that the evolution of VGE with the increase of voltage can be divided into four stages: microbubble stage, formation stage, fluctuation stage and stable stage. Corresponding to the fluctuation stage of VGE, the surface roughness of the workpiece can be reduced from the original Ra 0.7 μm to 0.2 μm in the voltage range of 200–400 V. It can be concluded that the fluctuation of VGE is the key to the effect of PEP, the fluctuation of the VGE makes the electrolyte constantly contact and separate from the workpiece surface. The electrochemical reaction occurs during contact, and plasma discharge channels are formed during separation. Additionally, the electrochemical reaction is the main cause of surface material removal, and the positive effect of plasma discharge is to produce a shock wave to remove electrolytic products on the surface of the workpiece. [ABSTRACT FROM AUTHOR]

Insects are exposed to cadmium stress since cadmium pollution has increasingly become a serious global environmental issue. However, until now few studies have paid attention to the effect of heavy metals on insect reproductive behaviors. In our study, the courtship behaviors, mating behaviors and fecundity of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) exposed to different concentrations of cadmium in artificial diets at larval stage were studied. The results showed that cadmium stress changed the courtship rhythm by significantly advancing or delaying the courtship starting time. Low dose of cadmium (0.2 mg/kg) increased the courtship frequency in the first two scotophases, but in the fourth phase, the two cadmium treatments reduced the frequency. The total courtship duration was significantly shortened in the first six scotophases except high dose of cadmium treatment (51.2 mg/kg) in the sixth dark phase. Paired adults did not mate after the seventh scotophase under low cadmium exposure, while high cadmium stress made the paired adults just copulate in the first four scotophases. The daily mating rate and total mating rate decreased with the increase in cadmium concentration. The number of eggs of low cadmium treatment was higher than that of control, but the difference was not significant; the number of eggs in high cadmium treatment was lower than that of control and low cadmium treatment. Our results indicate that cadmium exposure can disrupt the courtship rhythm for females and has negative influences on copulation behavior and high cadmium stress can reduce fecundity. Hence, the insect population increase will be affected by heavy metal pollution. Our study will provide scientific reference for environmental risk assessment of heavy metal pollution. [ABSTRACT FROM AUTHOR]

Impeller with narrow-vane is a typical thin-walled structural part of the turbine engine. The high-accuracy requirement for the impeller is difficult to achieve in the machining process due to its low structural stiffness and narrow machining domain. This paper proposes a framework for enhancing the milling accuracy of the thin-walled narrow-vane turbine impeller, which is made of NiAl-based superalloy. The proposed framework consists of a machinability study of the impeller material, a machining deformation analysis, and an error compensation. By studying the milling force and tool wear behavior experimentally, the machinability study yielded optimized process parameters for machining NiAl-based superalloy. A cantilever beam–based tool deformation model and a finite element analysis method model were developed respectively to analyze and predict the deformation of the milling tool in machining the impeller. A flexible and iterative compensation method was studied for decreasing the machining error when milling the impeller. The effectiveness of the proposed framework has been validated experimentally. The results show that the milling accuracy of the turbine impeller has been enhanced significantly. [ABSTRACT FROM AUTHOR]

To improve the neck-spinning processing quality of plunger components, a reliable finite element (FE) model was established and validated by the experimental spinning force. In the advanced FE model, an additional analysis step was added to obtain the pulling-out force, the axial clearance, and the swing angle of the plunger components after the neck-spinning process. Thus, the neck-spinning quality of the plunger components can be predicted. The results show that the simulated results using the FE model agree with the experimental results very well. The radial and axial spinning forces are approximate 3 and 2 times of the tangential spinning force, respectively. Finally, the influences of spinning parameters (e.g., feed rate and rotating speed) on the finished pulling-out force, axial clearance, and swing angle were evaluated in detail. The pulling-out force increases with increased feed rate, which tends to be stable with increased rotating speed. Compared with the stable tendency of axial clearance affected by feed rates, the axial clearance decreases significantly with increased rotating speeds. The swing angle of plunger components remains stable with different feed rate and rotating speed after the neck-spinning process. [ABSTRACT FROM AUTHOR]

In the present research, three typical cutting tool wear mechanisms (abrasive wear, adhesive wear, and diffusive wear) were taken into consideration in the FE simulation of cutting tool with a specific user-defined subroutine. Based on the influence of temperature on the cutting tool wear form, a novel wear rate model was built integrating Usui, Takeyama, and Attanasio wear rate equation. The high-speed cutting tests were carried out on Ti6Al4V to determine the proposed wear rate model constant. The cutting forces and rack face wear morphologies obtained from FE simulation match well with those from experimental cutting tests. Finally, the effect of cutting parameters on tool wear was studied by FEM. The simulation results show that the impact of the cutting speed on the cutting tool life is more significant than that of feed rate, and the preferred ranges of cutting speed and feed rate for extending cemented carbide cutting tool in high-speed dry cutting Ti6Al4V are 90–150 m/min and 0.10–0.20 mm/r, respectively. [ABSTRACT FROM AUTHOR]

Indentation test (Nanoindentation and Vickers indentation), diamond scratching and high spindle speed grinding are conducted to investigate the role of silicon (Si) in the surface damage behavior of reaction-bonded SiC/Si composites (RB-SiC/Si). Even though the addition of Si contributes to densifying the bulk materials and improving the toughness, the indentation and diamond scratching results firstly indicate that the cracks initiate at the SiC/Si interfaces due to the non-uniform deformation caused by the existence of Si, and the phase transformation of Si also leads to the pop-out effect during the nanoindentation and the diamond scratching test. The ground surface of RB-SiC/Si is characterized by scratching grooves and brittle fracture, indicating the ductile material removal mode and brittle material removal mode for RB-SiC/Si, respectively, and the surface reliefs form on the ground surface due to the different hardness between Si and SiC phases. Moreover, the phase transformation of Si contributes to the easy fracture of phase boundaries under the mechanical loading, and the accompanied volume change also results in the dislodgement of hard particles and the generation of surface burs on the ground surface. [ABSTRACT FROM AUTHOR]

Ti2AlNb alloy is a relatively newly developed high-temperature-resistant structural material due to its excellent mechanical properties, which is also regarded as one of the most difficult-to-cut materials. The aim of this study is to characterize the chip formation during the machining of Ti2AlNb intermetallic alloy due to its critical role in studying optimization of machining process variables. A geometry model of chip formation was established to analyze the influence of strain rate hardening effect and thermal softening effect on the flow stress in the shear zone. A series of orthogonal cutting tests and quick-stop cutting tests were conducted with varying cutting speeds and cutting depths to validate the evolutions of flow stress inside the shear band. Results associated with cutting forces, cutting temperature, chip morphology, and microhardness are discussed and compared with those of most commonly used Ti6Al4V alloy. It is shown that the cutting forces and cutting temperature of Ti2AlNb alloy are higher than those of Ti6Al4V alloy by 35.3 and 20%, respectively. The chip morphologies of Ti2AlNb alloy show very different characteristics with different cutting conditions (i.e., some very small sawtooth on the free surface of chips under low cutting speed, then transform into irregular serrated chips with increasing cutting speed, and to serrated chip with adiabatic shear band under high cutting speed), which correlate well with the evolutions of microhardness distribution. The chip morphologies and chip formation characteristics are dependent largely on the dynamic flow stress, which is sensitive to the competition of the thermal softening effect with strain rate hardening effect. [ABSTRACT FROM AUTHOR]

Continuous carbon fiber reinforced silicon carbide ceramic matrix composites (C/SiC) are promising materials in aerospace and space optical fields due to their excellent properties. However, poor machining quality resulted from surface/subsurface breakage is hard to meet precision requirements of some components. With an objective to study surface/subsurface breakage formation mechanism and improve machining quality of C/SiC composites, ultrasonic assisted grinding (UAG) and conventional grinding (CG) tests with a defined diamond grain distribution brazed grinding wheel were conducted. The surface/subsurface breakage types and formation mechanism were studied by comparative analysis of grinding force, micro-morphology of grinding surface/subsurface, and ground surface roughness. The results showed that main breakage types of different angle fibers in ground surface were lamellar brittle fracture and pit group originating from fracture and pullout of fibers, while breakage types of different angles fibers in ground surface were brittle fracture. Compared to CG, these breakages were reduced by UAG in varying degrees because it can reduce grinding force that determined fiber breakage. Consequently, because of the lower fiber breakages, the ground surface roughness Sa obtained by UAG was lower than CG and the maximum reduction was 12%. [ABSTRACT FROM AUTHOR]

In this article, the finite element model containing the varied coefficients of friction is established in order to improve the prediction accuracy of surface grinding temperature of particulate reinforced titanium matrix composites (PTMCs). The coefficients of friction, such as 0.46 for conventional-speed grinding and 0.21 for high-speed grinding, respectively, are determined according to the grinding forces ratios measured. Results obtained show that the relative error of experimental and predicted grinding forces is limited within 2∼9 %, while the relative error of experimental and predicted grinding temperatures values is controlled at 7∼15 %. The prediction accuracy is improved significantly based on the varied coefficients of friction in surface grinding of PTMCs. [ABSTRACT FROM AUTHOR]

Ultrasonic assisted grinding (UAG) is an outstanding technology suitable to machine advanced ceramics. During UAG, the effect of ultrasonic vibration on grinding process is mainly determined by matching performance between grinding and vibration parameters in theory. However, this problem is still lack of deep study. With an objective to study the matching performance deeply, conventional grinding (CG) and UAG tests were conducted. The effects of grinding parameters on grinding force, ground surface profile wave, and ground surface roughness between UAG and CG were studied. The results showed that the grinding force, ground surface profile wave height, and ground surface roughness during UAG were reduced in varying degrees compared to CG. Additionally, the reduction percentage that means the effect of ultrasonic vibration on grinding process decreased significantly with increasing grinding speed while affected slightly by increasing of feedrate and grinding depth. To deeply analyze this variety law of the ultrasonic vibration effect during UAG, a matching performance equation referred to grinding wheel diameter, grinding, and vibration parameters is proposed. When the grinding speed increases from 1.26 to 31.5 m/s for feedrate of 100 mm/min and grinding depth of 5 μm, reduction percentage in grinding force for UAG compared to CG ( K ) decreases from about 20 to 4 % and in ground surface roughness ( K ) decreases from 35 to 4 %. With regard to the average difference height (Δ h) between the UAG and CG profile waves, it decreases from 2.77 μm almost to zero. [ABSTRACT FROM AUTHOR]

This paper provides a state-of-the-art review on the investigations into the residual stresses in metallic structural materials generated by grinding. The materials covered include steels, titanium alloys, and nickel-based superalloys. The formation mechanisms of the residual stresses and their impacts are specifically discussed. Some major influential factors on the residual stresses formation in grinding, such as grinding wheel characteristics, dressing techniques, grinding parameters, cooling conditions, and properties of workpiece materials, are analyzed in detail. These include experimental measurement, modeling, simulation, knowledge-based monitoring, and fuzzy analysis. Finally, the paper highlights some important aspects of grinding-induced residual stresses for further investigation. [ABSTRACT FROM AUTHOR]

This article investigates the brazing-induced residual stresses in the polycrystalline cubic boron nitride (PCBN) abrasive grains based on finite element simulation. The effects of embedding depth and gap thickness on the residual stress distribution in brazed PCBN grains are discussed. Results obtained show that, compared with the Ag-Cu-Ti alloy joining CBN grains and AISI 1045 steel substrate, the AlN binder materials in the polycrystalline CBN grains always have a greater effect on the brazing-induced residual stresses; meanwhile, large residual tensile stresses usually exist at the interface between the microcrystalline CBN particles and AlN binders. In comparison to the embedding depth, the gap thickness has little influence on the brazing-induced residual stresses. Furthermore, compared with the other embedding depth, in the case of the embedding depth of 40 %, the residual stresses in the brazed PCBN grain are generally the lowest in the grain bottom and the largest in the grain top surface. Finally, the finite element model applied in the current simulation work is validated through measurement experiments of the brazing-induced residual stresses in the monocrystalline CBN grain. [ABSTRACT FROM AUTHOR]

The application of monolayer brazed diamond wheels in machining hard-brittle materials is always limited for the high transverse roughness on the ground surface of the workpiece. In the present investigation, a new dressing method, namely plate wheel dressing, was proposed for monolayer brazed diamond wheels in order to reduce the surface roughness of workpiece by micro-removing the over-protruded grits. To evaluate the effect of the dressing method, the grinding performance of the dressed diamond wheel was investigated in grinding SiC ceramics. Results obtained show that the contour of the grits was improved greatly and the quality of the workpiece was pretty good to meet the requirement of precision grinding. The transverse surface roughness R value reduced to the minimum value, i.e., 0.086 μm. This plate wheel dressing method can realize the precise dressing of the monolayer brazed diamond wheel. [ABSTRACT FROM AUTHOR]

This paper carries out a finite element (FE) analysis to investigate the effects of grinding speed (20 ∼ 400 m/s) and undeformed chip thickness (1 ∼ 8 μm) on chip formation during single grain grinding of nickel-based superalloy Inconel 718. Three factors related to the Johnson-Cook (J-C) constitutive model, i.e., the strain hardening, strain-rate hardening, and thermal-softening, were taken into account to determine the critical grinding speed. The results show that the chip segmentation frequency increases linearly with increasing the grinding speeds. It was found that the critical grinding speed is 150 m/s based on the variations of equivalent plastic strain, von Mises stress, and grinding force. It was also revealed that the effects of strain hardening and strain-rate hardening on the chip formation are more significant than that of the thermal softening when a grinding speed is below 150 m/s. However, if the grinding speed exceeds this critical value, thermal softening becomes a dominant factor. [ABSTRACT FROM AUTHOR]

The monolayer brazed wheels, which have several advantages such as high bonding strength, high chip storage space, and uniform grit spacing, have drawn much attention in the grinding of different-to-machine materials. As pursuing for higher machining efficiency, special attention has been devoted to high-speed grinding. However, when the grinding wheel is fabricated by conventional brazing technology, the thermal deformation of the wheel is remarkable, and the accuracy of brazed wheel cannot meet the needs of high-speed grinding. To take the challenge of the unexpected wheel deformation after brazing, a new brazing technology, named continuous induction brazing, was proposed to fabricate monolayer brazed cubic boron nitride (CBN) wheel with diameter d = 400 mm for high-speed grinding. The experiments and analysis revealed that chemical bonding between CBN grains and filler alloy was achieved. The maximum thermal deformation of the newly brazed wheel was less than 16 μm. High-speed grinding performance of the brazed CBN wheel for grinding of Inconel718 superalloy showed that the grinding wheel has good bonding strength. Moreover, a relatively satisfactory ground surface quality was achieved. [ABSTRACT FROM AUTHOR]

Based on farm field plot level survey data and laboratory test, we examine the determinants of the expression of Bt toxin in China's Bt cotton production. The results show that the expression of Bt toxin differs significantly among varieties. Even for the same variety the expression of Bt toxin also varies substantially among villages and among farmers in the same village. Econometric analyses show that after controlling for the effects of varieties and locations (or villages), farm management, particular applications of phosphate and potash fertilizers, and manure, has significant positive effects on Bt toxin expression in farmer's fields. In contrast to previous studies which showed that nitrogen fertilizer has a positive impact on expression of Bt toxin, this study shows that nitrogen fertilizer has no significant impact on expression of Bt toxin in farmer's fields. On the other hand, the expression of Bt toxin has a positive relationship with phosphate fertilizer, potash fertilizer and manure application. [ABSTRACT FROM AUTHOR]

It is recognized that grinding efficiency and ground surface quality are determined by grinding wheel performance. Additionally, the investigation on wear behavior is essential for evaluating the grinding wheel performance. There is a lack of research on the tool wear behavior during ultrasonic vibration-assisted grinding (UAG), whose grain motion trajectory differs from that in conventional grinding (CG). In the present work, CG and UAG tests of silicon carbide (SiC) were conducted in order to investigate the effects of ultrasonic vibration on the tool wear through tracking observation of grains. Meanwhile, the grinding forces and ground surface roughness correlated to the tool wear stages were studied. The results demonstrated that the main wear types during UAG were micro-fracture and macro-fracture which caused the wheel sharpening, while during CG, the main wear type was attritious wear that made the wheel blunt. As a result, UAG obtained lower and more stable grinding forces while slightly rougher ground surface in comparison with CG. [ABSTRACT FROM AUTHOR]

CBN-AlN composite abrasive grits and AISI 1045 steel were brazed using Ag-Cu-Ti active filler alloy by heating up to the temperature of 890, 900 and 920 °C, respectively, and then held at the temperature for 8 min. Optical microscope, scanning electron microscope and X-ray diffraction equipment were utilized to study the effects of heating temperature on the microstructure of the joining interface. The compressive strength of the brazed composite grits was also measured. The experimental results show that the atoms of Ti, Al, B and N have preferentially penetrated towards the joining interface of composite grits and filler alloy. The compounds of Ti-nitride, Ti-borides and TiAlN were formed in the reaction layer. Degradation effect was not made on the compressive strength of the CBN-AlN composite grits when the brazing process was carried out in the temperature range of 890-920 °C. [ABSTRACT FROM AUTHOR]

Joining experiments of CBN grains to AISI 1045 steel were conducted using Ag-Cu-Ti composite fillers containing TiX ( X=B or N) particles at 920 °C for 5 min. The influences of TiB and TiN particles on the interfacial microstructure features between CBN and filler were investigated comparatively. The experimental results show that TiN particles are more effective than TiB ones to control the interfacial reaction and particularly the resultants. Thermodynamic analysis reveals that the varied interfacial reaction induced by the addition of TiB and TiN particles is mainly atttributed to the activity change of the B and Ti elements in the brazing reaction system. [ABSTRACT FROM AUTHOR]

Grinding force model is an important tool for the selection and optimization of ultrasonic-assisted grinding of advanced ceramics. Meanwhile, there is still a lot of room for performance improvement and application expansion. In particular, it is generally recognized that the grinding wheel wear state directly affects the accuracy of grinding force model. To address these issues, a model for predicting the grinding force during ultrasonic-assisted face grinding (UAFG) of advanced ceramic materials was proposed in the present work based on the material removal mechanisms and the friction characteristics of the grain–workpiece interface under the action of ultrasonic vibration. UAFG tests were carried out on ZrO2 ceramics to verify the accuracy of the model. The results show that the average discrepancies between the predicted and measured normal and tangential forces are 7.4% and 8.1%, respectively. Finally, the tool wear tests reveal that with the gradual wear of the tool, the grinding force first decreases and then increases, and the accuracy of the model follows the opposite trend. Furthermore, the abrasive wear state has a significant effect on the surface material removal mechanism during ultrasonic-assisted grinding. When the cutting-edge morphology is regular and micro-crushed abrasive grains are predominant, the material removal mechanism is a combination of plastic removal and brittle fracture. When macro-crushed abrasive grains and abrasive fracture prevail, the material removal mechanism is dominated by brittle fracture, while the material removal mechanism is dominated by plastic removal when abrasive platform is predominant. [ABSTRACT FROM AUTHOR]