Effects Of Recasting On The Castability,Composition And Microstructure Of Non-Precious Ceramic Alloy

Objective: To investigate the effects of recasting on the castability,composition and microstructure of non-precious ceramic alloy.Methods: The non-precious ceramic alloy was recasted 6 times in argon protection. (1) The castability of each generation non-precious ceramic alloy was determined by the ability of the alloy to cast a mesh pattern made from wax sieve. After being invested and casted, the pattern casting was then examined to determine the total number of filament segments that were successfully casted. Then, the castability value (Cv) of each generation alloy was obtained. (2) Each generation non-precious ceramic alloy were minted into square plates in argon protection. Then, the original alloy and each generation square plates were analyzed by x-ray fluorescence spectrometry (XRF) for qualitative and semi-quantitative analysis. (3)The microstructure and the phase structure of original alloy and each generation castings which had been polished by buffing machine were observed and analyzed by metallographic microscope and x ray diffractometer (XRD).Results:(1) There was no significant difference of castability from 1st to 5th generation castings which were casted by non-precious ceramic alloy in argon protection(P>0.05). There was a significant difference of castability between 1st generation castings and 6th generation castings(P<0.05). (2) There was no significant difference on main composition between original alloy and each generation castings which were analyzed by x-ray fluorescence spectrometry (XRF) for semi-quantitative analysis. (3) With the increase of recast times, the size of dendritic crystal grain in the castings coarsening, shrinkage cavity,porosity and inclusion gradually increased. There was no significant difference of phase structure between original alloy and each generation castings.Conclusions: There is no significant change on the castability of non-precious ceramic alloy, which is recasted for 5 times in argon protection. And there was no significant difference of main composition and phase structure between original alloy and each generation castings. With the increase of recast times, the size of dendritic crystal coarsening, shrinkage cavity,porosity and inclusion gradually increased.