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The paper presents the results of the analysis of cooling curves of cast iron with approximately eutectic composition rasterized at different rates of cooling and ingot crystallization. The test samples were in the form of rods with a diameter of 30,0.mm and a coagulation modulus M = 0.75 cm. They were cast in a sand mould made of furan mass placed on a chill in the form of a cast-iron plate, with which one of the front surfaces of the rod casting was in contact. In this way, a differentiated cooling rate along the rod was achieved. At selected distances from the chiller (5, 15, 25, 25 and 45 mm) thermocouple moulds were placed in the cavity to record the cooling curves used in thermal (AT) and derivation (ATD) analysis. The solidification time of the ingot in the part farthest from the chiller was about 200s, which corresponds to the solidification time in the test cup AT. An analysis of the recorded cooling curves was performed in order to determine the values of characteristic points on the AT curve (Tsol. Tliq, ΔTrecal., τclot, etc.). Relationships between cooling time and rate and characteristic points on AT and ATD curves were developed. For example, Tsol min changes in the range of 1115 - 1145 for the range of cast iron solidification times in the selected ingot zone from ~ 70 to ~ 200 s, which corresponds to the process speed from 0.0047 to 0.014 [1/s]. The work also includes an analysis of other characteristic points on the AT and ATD curves as functions of the solidification rate of cast iron of the same composition. [ABSTRACT FROM AUTHOR]

The investigation results of the kinetics of binding ceramic moulds, in dependence on the solid phase content in the liquid ceramic slurries being 67, 68 and 69% - respectively, made on the basis of the aqueous binding agents Ludox AM and SK. The ultrasonic method was used for assessing the kinetics of strengthening of the multilayer ceramic mould. Due to this method, it is possible to determine the ceramic mould strength at individual stages of its production. Currently self-supporting moulds, which must have the relevant strength during pouring with liquid metal, are mainly produced. A few various factors influence this mould strength. One of them is the ceramic slurry viscosity, which influences a thickness of individual layers deposited on the wax model in the investment casting technology. Depositing of layers causes increasing the total mould thickness. Therefore, it is important to determine the drying time of each deposited layer in order to prevent the mould cracking due to insufficient drying of layers and thus the weakening of the multilayer mould structure.

A large number of defects of castings made in sand moulds is caused by gases. There are several sources of gases: gases emitted from moulds, cores or protective coatings during pouring and casting solidification; water in moulding sands; moisture adsorbed from surroundings due to atmospheric conditions changes. In investigations of gas volumetric emissions of moulding sands amounts of gases emitted from moulding sand were determined - up to now - in dependence of the applied binders, sand grains, protective coatings or alloys used for moulds pouring. The results of investigating gas volumetric emissions of thin-walled sand cores poured with liquid metal are presented in the hereby paper. They correspond to the surface layer in the mould work part, which is decisive for the surface quality of the obtained castings. In addition, cores were stored under conditions of a high air humidity, where due to large differences in humidity, the moisture - from surroundings - was adsorbed into the surface layer of the sand mould. Due to that, it was possible to asses the influence of the adsorbed moisture on the gas volumetric emission from moulds and cores surface layers by means of the new method of investigating the gas emission kinetics from thin moulding sand layers heated by liquid metal. The results of investigations of kinetics of the gas emission from moulding sands with furan and alkyd resins as well as with hydrated sodium silicate (water glass) are presented. Kinetics of gases emissions from these kinds of moulding sands poured with Al-Si alloy were compared.

The results of researches of sorption processes of surface layers of components of sand moulds covered by protective coatings are presented in the hereby paper. Investigations comprised various types of sand grains of moulding sands with furan resin: silica sand, reclaimed sand and calcined in temperature of 700°C silica sand. Two kinds of alcoholic protective coatings were used - zirconium and zirconium - graphite. Tests were performed under condition of a constant temperature within the range 30 - 35°C and high relative air humidity 75 - 80%. To analyze the role of sand grains in sorption processes quantitavie moisture sorption with use of gravimetric method and ultrasonic method were used in measurements. The tendency to moisture sorption of surface layers of sand moulds according to the different kinds of sand grains was specified. The effectiveness of protective action of coatings from moisture sorption was analyzed as well.

The paper presents the results of research on the kinetics of the binding process of self-hardening moulding sands with an organic binder under conditions of forced air flow at various pressure values. Three moulding sands made using urea-furfuryl resin Furanol FR75A technology were studied. The moulding sands were prepared on a base of quartz sand with an average grain size of dL = 0.25, 0.29 and 0.37 mm, with permeability values of 306, 391 and 476 m²/108Pa · s (for -0 = 1.60, 1.60 and 1.61 g/cm³, respectively). The research was conducted for a resin content of 1% with a constant proportion of hardener to resin, which was equal to 50%. Samples of the tested moulding sands were blown with air at pressures of 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 bar. The kinetics of the hardening process was monitored using ultrasound technology, according to a previously developed methodology [1]. The research was carried out on an ultrasound testing station equipped with a temperature chamber and an airflow reducer. The tests were conducted at a temperature of 20°C, and of the air flow pressure on the changes in ultrasonic wave velocity in the hardening mouldins sand as a function of time, the kinetics of the hardening process, and the degree of moulding sand hardening were determined. Additionally, the influence of the moulding sand permeability on the course of the hardening process at a constant air flow pressure was determined. [ABSTRACT FROM AUTHOR]

In lost wax technology, self-supporting ceramic moulds are made, which must have adequate strength after being filled with liquid metal. The final structural strength is determined by such factors as the thickness of the individual layers applied to the wax model resulting from the viscosity of the liquid mass, the specific strength of the layers formed, and the heat treatment of the moulds. The development of technology and materials is moving in the direction of increasing the specific strength of self-supporting ceramic moulds. The consequence of this is that the final strength of these moulds is too high, making it difficult to knock castings out of the moulds. Removing mould remnants from holes, closed spaces of the casting, corners, sharp edges, variable cross sections and etc. is cumbersome. In order to remove mould remnants from the casting, a method is used to dissolve them in heated solutions of suitable chemical composition and reaction. The paper presents the results of research on a new solution, the essence of which is the production of layers in a ceramic mould, in the middle zone of the mould, characterized by a significantly reduced final strength, achieved after firing. These layers are produced using a different liquid ceramic mass than the base one, based on an organic binder. As a result, thanks to the embedded layer, very good knockout of castings is achieved and separation of residual ceramic mass. Special layers can be incorporated over the entire surface or only in those places where the bonding of the casting surface and ceramic mass occurs. [ABSTRACT FROM AUTHOR]

The new investigation method of the kinetics of the gas emission from moulding sands used for moulds and cores is presented in this paper. The gas evolution rate is presented not only as a function of heating time but also as a function of instantaneous temperatures. In relation to the time and heating temperature the oxygen and hydrogen contents in evolving gases was also measured. This method was developed in the Laboratory of Foundry Moulds Technology, Faculty of Foundry Engineering, AGH. Gas amounts which are emitted from the moulding sand at the given temperature recalculated to the time unit (kinetics) are obtained in investigations. Results of investigations of moulding sand with furan resin are presented - as an example - in the paper.

The results concerning emission of gases from two commercial graphite protective coatings for moulds and cores (water and alcoholic) are given in the hereby paper. Investigations were performed in two systems. One of the systems was corresponding to conditions occurring inside the mould cavity immediately after its pouring with liquid metal (Method 1), while the second was simulating conditions deep inside the mould at a certain distance from the casting (Method 2). Investigations were carried out in the CO2 atmosphere and in the air. The water protective coating generated 1.5 to 3 times larger volume of gases than the alcoholic coating (in dependence on the measuring method and atmosphere). The smallest differences occurred in the air atmosphere, while the largest in the CO2 atmosphere.

The results of investigations of the sorption process of surface layers of sand moulds covered by zirconium and zirconium - graphite alcohol coatings are presented in the paper. Investigations comprised two kinds of sand grains (silica sand and reclaimed sand) of moulding sand with furan resin. Tests were performed under conditions of a high relative air humidity 75 - 85% and a constant temperature within the range 28 – 33°C. To evaluate the effectiveness of coatings protective action from moisture penetration into surface layers of sand moulds gravimetric method of quantitavie moisture sorption and ultrasonic method were applied in measurements.

Issues connected with high quality casting alloys are important for responsible construction elements working in hard conditions. Traditionally, the quality of aluminium casting alloy refers to such microstructure properties as the presence of inclusions and intermetallic phases or porosity. At present, in most cases, Quality index refers to the level of mechanical properties – especially strength parameters, e.g.: UTS, YS, HB, E (Young’s Modulus), K1c (stress intensity factor). Quality indexes are often presented as a function of density. However, generally it is known, that operating durability of construction elements depends both on the strength and plastic of the material. Therefore, for several years now, in specialist literature, the concept of quality index (QI) was present, combines these two important qualities of construction material. The work presents the results of QI research for casting hypoeutectic silumin type EN AC-42100 (EN AC-AlSi7Mg0.3), depending on different variants of heat treatment, including jet cooling during solution treatment.

The obtained results of heating of sand moulds with binders by means of a thermal radiation of liquid metal are presented in this study. Standard samples for measuring Rg made of the tested moulding sands were suspended at the lower part of the cover which was covering the crucible with liquid metal (cast iron), placed in the induction furnace. The authors own methodology was applied in investigations. The progressing of the samples surface layers heating process was determined as the heating time function. Samples of a few kinds of moulding sands with chemical binders were tested. Samples without protective coatings as well as samples with such coatings were tested. The influence of the thermal radiation on bending resistance of samples after their cooling was estimated. The influence of several parameters such as: time of heating, distance from the metal surface, metal temperature, application of coatings, were tested. A very fast loss of strength of moulding sands with organic binders was found, especially in cases when the distance between metal and sample surfaces was small and equaled to 10÷15 mm. Then, already after app. 15 seconds of the radiation (at Tmet=1400°C), the resistance decreases by nearly 70%. Generally, moulding sands with organic binders are losing their strength very fast, while moulding sands with water glass at first increase their strength and later slightly lose. The deposition of protective coatings increases the strength of the mould surface layers, however does not allow to retain this strength after the metal thermal radiation.

The investigation results of the thermal conductivity of the selected group of moulding sands with chemical binders, mainly organic, are presented in the hereby paper. Studies encompassed also moulding sands into which additions improving the thermal conductivity were introduced. Two testing methods were applied, i.e. investigations at a steady and unsteady temperature zone. For investigations at a steady temperature zone the new original experimental stand was designed and built, adapted also for testing moulding sands with binders undergoing destruction at relatively low temperatures.

W pracy przedstawiono wyniki badań odporności na zmęczenie cieplne dwóch gatunków żeliwa ADI (EN-GJS-1200-2 i EN-GJS-800-8). Badania prowadzono na autorskim stanowisku badawczym stosując oporowe nagrzewanie próbek, wg metody L.F. Cottina. Odporność na zmęczenie cieplne jest podstawowym kryterium w ocenie przydatności tworzywa (materiału) na formy metalowe, które podlegają cyklicznemu nagrzewaniu. Oceniono wpływ maksymalnej temperatury (Tmax,) cykli cieplnych na ich liczbę do pęknięcia próbki, analizowano zmiany struktury żeliwa ADI. zmiany twardości i wytrzymałości. Stwierdzono, iż przy cyklicznym nagrzewaniu do

The results of investigations of humidity migration in near surface layers of sand mould during processes of penetration and drying of protective coatings are presented in the hereby paper. The process of the humidity exchanging between surroundings and moulding sands as porous materials, is widely described in the introduction. In addition, the humidity flow through porous materials, with dividing this process into stages in dependence of the humidity movement mechanism, is presented. Next the desorption process, it means the humidity removal from porous materials, was described. Elements of the drying process intensity as well as the water transport mechanisms at natural and artificial drying were explained. The innovative research stands for measuring resistance changes of porous media due to humidity migrations was applied in investigations. Aqueous zirconium coatings of two apparent viscosities 10s and 30s were used. Viscosity was determined by means of the Ford cup of a mesh clearance of 4mm. Coatings were deposited on cores made of the moulding sand containing sand matrix, of a mean grain size dL = 0.25 mm, and phenol-formaldehyde resin. Pairs of electrodes were placed in the core at depths: 2, 3, 4, 5, 8, 12 and 16 mm. Resistance measurements were performed in a continuous way. The course of the humidity migration process in the core surface layer after covering it by protective coating was determined during investigations. Investigations were performed in the room where the air temperature was: T = 22 °C but the air humidity was not controlled, as well as in the climatic chamber where the air temperature was: T = 35 °C and humidity: H = 45%. During the research, it was shown that the process of penetration (sorption) of moisture into the moulding sand is a gradual process and that the moisture penetrates at least 16 mm into the sand. In the case of the drying (desorption) process, moisture from the near-surface layers of the moulding sand dries out much faster than moisture that has penetrated deeper into the sand. [ABSTRACT FROM AUTHOR]

Abstract Introduction While adjuvant therapy of early-stage non-small-cell lung cancer (NSCLC) is widely accepted, literature data concerning neoadjuvant treatment provide contradictory results with both improved and unaffected survival rates. Also, data concerning potential effects of neo-adjuvant therapy on cellular level are scarce. Objective The aim of present study was to analyze the effect of chemotherapy followed by surgical resection on several key biological markers of tumor growth (TGF-β, VEGF), apoptosis (sAPO-1/Fas/CD95) and invasiveness (TIMP-1) assessed in the sera of NSCLC early-stage patients (IB-IIIA). Materials and methods Measurements were performed by ELISA method in blood serum from 24 NSCLC patients (I-IIIA) collected prior therapy, one day before surgery and 3 days after. Results TGF-β serum concentrations were significantly lower after both chemotherapy (P < 0.05) and surgery (P < 0.01) in comparison to the baseline. VEGF levels decreased following NEO therapy with subsequent significant up-regulation after surgery (P < 0.001). Interestingly, post-surgery serum VEGF strongly correlated with TGF-β concentration (r = 0.52, P = 0.014). No significant differences were observed for serum sAPO-1/CD95/FAS as well as TIMP-1 concentrations at any of three evaluated time-points. Conclusion Neoadjuvant treatment of early-stage NSCLC affects mostly mechanisms responsible for tumor growth and vascularization. Its effect on cancer cells apoptotic activity needs further evaluation.

Two standardised grades of spheroidal cast iron determined in standard EN PN 1563 - 1997 as: EN-GJS-350 - 22LT (T = -40°C) and EN GJS 400 - 18LT (T = -20°C) are intended for work at low temperatures: -20 and -40oC. The main mechanical property of these cast iron grades is a high impact strength at a work temperature down to: -40°C. A series of controlled melts was performed to optimise the production technology of spheroidal cast iron, which in as-cast state is characterised by ferritic matrix (the best without any pearlite), fine precipitates of nodular graphite and high purity (without non-metallic inclusions). Variable structures of metal charges and various spheroidisation techniques (the modification methods) (slender ladle with a tight cover - Tundish technology as well as the technology with cored wire) were applied in the research. In order to obtain refinement of graphite precipitates and to achieve the ferritic matrix multistage inoculations of technologies were applied. Cast iron was subjected to refining to limit non-metallic inclusions since they decrease the impact strength. The production process of cast iron was controlled by the thermal derivative analysis at the stage of initial cast iron and after its secondary metallurgy (modification and inoculation). It was pointed out, that the reproducible production of cast iron for work at low temperatures was only possible when all elements of the technological process were strictly adhered to. It was pointed out, in the hereby paper, that: it should be strived to maintain Si content not higher than 2.50÷2.60%, which at producing spheroidal cast iron is sometimes difficult and requires using a lot of pig iron in the metal charge. For a fast assessment of the cast iron quality, concerning its impact strength, the proposed - in the hereby paper - index quality (IQu) can be applied. It is determined on the bases of measuring the cast iron hardness and propagation velocity of ultrasound wave. [ABSTRACT FROM AUTHOR]

The results of investigations of plasticity of moulding sands with binders obtained by measuring deflection angles in the single point bend test in dependence on their hardening degree are presented in the hereby paper. Shaped samples made of moulding sands obtained in the technology with urea-furfuryl resin Furanol FR75A and in the technology with water glass, were subjected to various tests. Shaped samples were made on the quartz matrix of a medium grains size 𝑑𝑙 = 0,29 𝑚𝑚. Investigations were performed for the resin content being 1% and 2%, at a constant proportion of a hardener versus resin -- equal 60%. In the case of sands from the technology with water glass, investigations were performed for 3.5% of water glass versus sand matrix and 0.35% of Flodur. Plasticity tests were carried out with using the strength machine with a continuous recording of a sample deflection value. Measurements of deflection angles values in the bend test were performed on a series of simultaneously made samples at constant time intervals from the moment of their making. To determine the sand hardening degree the ultrasound technique was applied, according to the previously developed methodology [1]. Every time from the obtained results the characteristic of the growing stress as a function of deflection was prepared (𝜎). In addition, for the tested group of moulding sands, empirical relationships between the maximum deflection angle (αmax) in the bend test and the hardening degree were determined (Sx): α = f(Sx). [ABSTRACT FROM AUTHOR]

Cast iron destined for spheroidization is usually characterized by a near-eutectic chemical composition, which is a result of the necessity of maintaining its high graphitizing ability. This graphitizing ability depends mainly on the chemical composition but also on the so-called physical-chemical state. This, in turn, depends on the melting process history and the charge structure. It happens quite often, that at very similar chemical compositions cast irons are characterized by different graphitizing abilities. The hereby work concerns searching for the best method of assessing the graphitizing abilities of near-eutectic cast iron. The assessment of the graphitizing ability was performed for cast iron obtained from the metal charge consisting of 100% of special pig iron and for synthetic cast iron obtained from the charge containing 50% of pig iron + 50% of steel. This assessment was carried out by a few methods: wedge tests, thermal analysis, microstructure tests as well as by the new ultrasonic method. The last method is the most sensitive and accurate. On the basis of the distribution of the wave velocity, determined in the rod which one end was cast on the metal plate, it is possible to determine the graphitizing ability of cast iron. The more uniform structure in the rod, in which directional solidification was forced and which had graphite precipitates on the whole length, the higher graphitizing ability of cast iron. The homogeneity of the structure is determined by the indirect ultrasonic method, by measurements of the wave velocity. This new ultrasonic method of assessing the graphitizing ability of cast iron of a high Sc (degree of eutectiveness) and CE (carbon equivalent) content, can be counted among fast technological methods, allowing to assess the cast iron quality during the melting process. [ABSTRACT FROM AUTHOR]

This paper presents a new stand for studying the linear shrinkage kinetics of foundry alloys. The stand is equipped with a laser displacement sensor. Thanks to this arrangement, the measurement is of a contactless nature. This solution allows for the elimination of errors which occur in measurements made using intermediary elements (steel rods). The supposition of the expansion (shrinkage) of the sample and the expansion of the heated rod lead to the distortion of the image of the actual dimensional changes of the studied sample. A series of studies of foundry alloys conducted using the new stand allowed a new image of shrinkage kinetics to be obtained, in particular regarding cast iron. The authors introduce in the study methodology a real-time measurement of two linked quantities; shrinkage (the displacement of the free end of the sample) and temperature in the surface layer of the sample casting. This generates not only a classic image of shrinkage (S) understood as S = f (t), but also the view S = f (T). The latter correlation, developed based on results obtained using the contactless method, provide a new, so far poorly known image of the course of shrinkage in foundry alloys, especially cast iron with graphite in the structure. The study made use of hypo- and hypereutectic cast iron in order to generate an image of the differences which occur in the kinetics of shrinkage (as well as in pre-shrinkage expansion - expansion occurs during solidification). [ABSTRACT FROM AUTHOR]

The graphite form in cast iron is the structure parameter deciding on its all physical and mechanical properties. Three basic forms of graphite: flake, vermicular (compact) and nodular (spheroidal) are singled out in standard cast iron grades, without a heat treatment. Standards of individual grades of cast iron the most often allow only the homogeneous graphite form, sometimes with addition of 5÷10% of the other form. The interesting and - in the authors opinion - future-oriented material can constitute cast iron in which various forms of graphite are present, e.g. in comparative amounts: spherical and vermicular cast irons. Cast iron within which graphite occurs in two or three forms was named „Vari-Morph” (VM) cast iron, i.e. the one in which spherical and vermicular or vermicular and flake graphite occur in a wide range of proportions. The results of investigations of these new cast iron grades and their properties are presented in the hereby paper. [ABSTRACT FROM AUTHOR]

Fatigue investigations of two 4XXX0-series aluminum alloys (acc. PN-EN 1706) within a range of fewer than 104 cycles at a coefficient of cycle asymmetry of R = -1 were performed in the current paper. The so-called modified low-cycle test, which provided additional information concerning the fatigue life and strength of the tested alloys, was also performed. The obtained results were presented in the form of diagrams: stress amplitude sa - number of cycles before damage N. On the basis of the microscopic images of sample fractures, the influence of the observed casting defects on the decrease of cycle numbers at a given level of stress amplitude were analyzed. Based on the images and dimensions of the observed defects, stress intensity factor KI was analytically determined for each. Their numerical models were also made, and stress intensity factor KI was calculated by the finite element method (FEM). [ABSTRACT FROM AUTHOR]

Gas emission from casting moulds, cores and coatings applied for sand and permanent moulds is one of the fundamental reasons of casting defects occurrence. In the previous studies, gas emission was measured in two ways: normalized, in which the evolving gas volume was measured during heating of the moulding sand sample in a sealed flask, or by measuring the amount of gas from sand core (sample) which is produced during the pouring of liquid metal. After the pouring process the sand mould is heated very unequally, the most heated areas are layers adjacent to the liquid metal. The emission of gas is significantly larger from the surface layer than from the remaining ones. New, original method of measuring kinetics of gas emission from very thin layers of sand moulds heated by liquid metal developed by the authors is presented in the hereby paper. Description of this new method and the investigation results of kinetics of gas emission from moulding sand with furan and alkyd resin are shown. Liquid grey cast iron and Al-Si alloy were used as a heat source in the sand moulds. Comparison of the kinetics of gas emission of these two kinds of moulding sands filled with two different alloys was made. The momentary metal temperature in sand mould was assigned to the kinetics of gas emission, what creates a full view of the possibility of formation of casting defects of the gaseous origin. Moulding sand with alkyd resin is characterized by larger gas emission; however gases are emitted slower than in the case of moulding sands with furan resin. This new investigation method has a high repeatability and is the only one which gives a full view of phenomenon's in the surface layer which determines quality of the casings. The obtained results are presented on several graphs and analyzed in detail. They have a great application value and can be used in the production of iron as well as light metal alloy castings. [ABSTRACT FROM AUTHOR]

The investigation results of the kinetics of binding ceramic moulds, in dependence on the solid phase content in the liquid ceramic slurries being 67, 68 and 69% - respectively, made on the basis of the aqueous binding agents Ludox AM and SK. The ultrasonic method was used for assessing the kinetics of strengthening of the multilayer ceramic mould. Due to this method, it is possible to determine the ceramic mould strength at individual stages of its production. Currently self-supporting moulds, which must have the relevant strength during pouring with liquid metal, are mainly produced. A few various factors influence this mould strength. One of them is the ceramic slurry viscosity, which influences a thickness of individual layers deposited on the wax model in the investment casting technology. Depositing of layers causes increasing the total mould thickness. Therefore, it is important to determine the drying time of each deposited layer in order to prevent the mould cracking due to insufficient drying of layers and thus the weakening of the multilayer mould structure. [ABSTRACT FROM AUTHOR]

The new investigation method of the kinetics of the gas emission from moulding sands used for moulds and cores is presented in this paper. The gas evolution rate is presented not only as a function of heating time but also as a function of instantaneous temperatures. In relation to the time and heating temperature the oxygen and hydrogen contents in evolving gases was also measured. This method was developed in the Laboratory of Foundry Moulds Technology, Faculty of Foundry Engineering, AGH. Gas amounts which are emitted from the moulding sand at the given temperature recalculated to the time unit (kinetics) are obtained in investigations. Results of investigations of moulding sand with furan resin are presented - as an example - in the paper. [ABSTRACT FROM AUTHOR]

The aim of the investigations was the development of the protective coating and the method of its preparation intended for foundry moulds and cores. The selection of the proper surface-active agent, allowing graphite wetting by water in order to form homogenous water composition with the remaining components of the coating, was especially important. [ABSTRACT FROM AUTHOR]

Currently offered devices for the hardness measuring or indices of the mould strength, are presented in the hereby paper. The presented results allow to compare approximately the indications of individual devices of different types. The description of the author's own microprocessor tester for the quality assessment of the sand foundry moulds, is shown. On the bases of the measurements results it is possible, to evaluate indirectly, the mould apparent density in the selected points, as well as several other properties. [ABSTRACT FROM AUTHOR]

Multi-layer ceramic moulds are built of slurry and a refractory material forming their matrices. From the moment when the European Union introduced regulations concerning the environment protection requiring substitution of alcoholic binders by aqueous binders, several difficulties in making moulds occurred. The influence of selected factors on drying ceramic moulds applied in the investment casting technology was determined by the gravimetric method. It was found that each successive layer, of a similar thickness, is drying longer than the previous one. The drying time of layers forming a deep cavities is several times longer as compared with drying open surfaces (external). Extension scale of the drying time is a function of the slenderness of cavities. [ABSTRACT FROM AUTHOR]

Investigation results of the drying rate of the selected protective coatings (water and alcohol) are presented in the article. Coating drying rate was determined for the first and second layers. The coating was applied to moulding sand cores. The rate of drying coatings were tested for three coating apparent viscosities estimated by means of the Ford 4 mm cup. Drying rates of the protective coating were examined by using the gravimetric technique and ultrasonic technique. Measurements were carried out in a continuous way under controlled conditions: constant ambient temperature and air humidity. Research shows that the drying time of the second coating layer is longer by 20 - 30 % than the first layer. [ABSTRACT FROM AUTHOR]

The article focused on researching the influence of Ti, B, Sr and Na as a modifying treatment elements for Al-Si alloys. The influence of alloying additives such as Cu and Cr was studied. Tensile strength Rm, elongation A5 and HB hardness was analysed, as well as the influence of the above-mentioned elements on the microstructure and solidification of alloys containing a varied content of Si, within the 7 ÷ 16 % range. The influence of heat treatment on the alloy properties was also researched. [ABSTRACT FROM AUTHOR]