Abstract
Experimental work was carried out to analyze the effect of impurities and the determination of optimal structure of the pouring gate system on the quality of titanium castings during the centrifugal casting.Is was established by atomic absorption spectrometric analysis that the chemical reactions of high-temperature interaction of titanium with refractory oxides go deep with the formation of not only intermediate suboxides, but also pure magnesium, aluminum and silicon. There were determined the conditions where it is possible to release hydrogen from liquid or solidifying titanium alloys TL3, TL5 and its participation in the formation of structural voids and shells by pouring titanium castings using a centrifugal method. It was found that by the production of titanium shaped castings in periclase molds based on MgO, the hydrogen content expands the shrinkage shells and pores in the castings. Respectively, it is necessary in the initial ingots (electrodes) that the hydrogen content should be less than 0.003%, and calcination of periclase molds shall be performed at T = 1000-1050°C.Optimal structure and sizes of the pouring gate system and special mold pattern were developed to produce high-quality titanium castings.
Keywords:
hydrogen solubility, atomic absorption spectroscopic analysis, equilibrium systems, dissociation of gases and vapors, refractory oxides, high chemical gas release, pouring gate system