Investigations of Properties of Wax Mixtures Used in the Investment Casting Technology – New Investigation Methods

The results of testing of the selected group of wax mixtures used in the investment casting technology, are presented in the paper. Themeasurements of the kinetics of the mixtures shrinkage and changes of viscous-plastic properties as a temperature function wereperformed. The temperature influence on bending strength of wax mixtures was determined

The influence of the shape of wax pattern on the kinetics of drying of ceramic moulds

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

Rheological properties of ceramic slurries with colloidal binders used in the investment casting technology

The article presents results of analyses of ceramic slurries made using materials currently tested in this technology, i.e.: colloidal silica (Ludox AM and Ludox SK) as a binder and Al2O3 as the ceramic matrix material. To characterise the binder, the size of colloidal binder particles, the Zeta potential and the binder pH were determined. Rheological properties were studied for slurries whose proportion of the (technologically justified) solid phase amounted to: 73; 74; 75 %. The impact of the solid phase proportion on the thickness of subsequent coats applied to the wax model, the dynamic viscosity and the density was determined. Research also included the impact of the size of matrix grains and the temperature on the above properties

The drying kinetics of protective coatings used on sand molds

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

Influence of refining treatments on the properties of Al-Si alloys

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

Copper alloys in investment casting technology

This paper presents research results in the field of casting technology of copper and copper alloys using the investment casting technology, both from historical as well as modern technology perspective. The analysis of exemplary elements of the old casting moulds is included, as well as the Bronze Age casts. The chemical content of various copper alloys was determined and the application of lost wax method was confirmed in the Bronze Age workshop. At present, investment casting method is used for manufacturing high-quality casts, especially products for power engineering that is why it demands respecting very rigorous technological requirements. The casts were characterised based on microstructure research, chemical composition and conductivity in relation to oxygen content