【作者】 赵伟；

【导师】 程辉；

【作者基本信息】 福建医科大学 ， 口腔临床医学， 2008， 硕士

【摘要】 目的:研究反复熔铸对非贵金属烤瓷合金铸流率、化学成分、微观组织结构的变化的影响。方法:(1)采用网状试样法,将非贵金属烤瓷合金进行反复熔铸,铸造出各代的网状试件,检查网状铸件的完整性,计算铸造完整的网格片段数占蜡网模型网格总片段数的百分比即铸流率(Cv)值,并进行方差统计分析、比较。研究反复熔铸对非贵金属烤瓷合金铸流率的影响(2)非贵金属烤瓷合金进行反复熔铸6次,铸造出各代的化学成分检测试样,应用X射线荧光光谱仪(XRF)对非贵金属烤瓷合金原始合金和反复熔铸后铸成的各代试样进行定性半定量分析。研究反复熔铸对非贵金属烤瓷合金化学成分的影响(3)应用正置式反射金相显微镜对经过表面抛光后的非贵金属烤瓷合金原始合金和反复熔铸后铸成的各代试样的金相显微结构进行观察;应用X射线粉末衍射仪对非贵金属烤瓷合金原始合金和反复熔铸后铸成的各代试样进行物相分析。研究反复熔铸对非贵金属烤瓷合金微观组织结构的影响。结果:在真空加压氩气保护的铸造环境下(1)非贵金属烤瓷合金经过1到5次的反复熔铸,铸流率的变化无统计学意义(P>0.05);反复熔铸6次后,第VI网状试件的铸流率与第I代网状试件的铸流率的差别有统计学意义(P<0.05)。(2)非贵金属烤瓷合金的主要元素组分为Ni、Cr、Mo、Al、Be。经过1到6次的反复熔铸,这5种主要元素所占的质量百分数(wt%)在半定量分析中没有显著差异(3)厂家提供的原始非贵金属烤瓷合金的金相结构为树枝状共晶结构,其枝晶的大小较一致,排列有序,夹杂物很少。熔铸后的非贵金属烤瓷合金其枝晶粗化,枝晶排列较熔铸前稍显紊乱,晶间相(基质)增多。并且合金内部夹杂物的含量以及缩孔、缩松的数量分布随着反复熔铸次数的增加而逐渐增多增广。反复熔铸后非贵金属烤瓷合金的物相结构没有发生明显变化。结论:在真空加压氩气保护的铸造环境下,非贵金属烤瓷合金可以反复熔铸5次铸流率没有发生变化,其各主要元素组分的质量百分数和物相结构随着反复熔铸次数的增多没有发生显著变化,随着熔铸次数的增多其枝晶粗化,合金内部夹杂物和铸造缺陷增多。更多还原

【Abstract】 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.更多还原