对4种国外磷酸盐包埋料的组成结构及性能的研究

The composition, structure and properties of the phosphate-bonded investment

目的 本文对国外四种磷酸盐包埋料进行了研究测试,从而了解磷酸盐包埋料的组成结构及性能。方法 采用X衍射检测包埋料的组成,电子探针EMPA检测其显微结构,检测显气孔率、体积密度、耐压强度、凝固膨胀、热膨胀来了解物理性能。结果 X衍射结果显示磷酸盐包埋料的主要成分是石英和方石英。结合剂为磷酸盐,主要为氧化镁及磷酸二氢铵。显微结构可看出包埋料由粗颗粒骨料和细颗粒基质粉料组成,骨料均匀地分布于基质结合相中,结合相由大量NH_4MgPO_4·6H_2O针柱状晶体相互交织而成。结论 磷酸盐包埋料的物理性能与它的组成及结构关系密切。

Objective The four foreign phosphate-bonded investments were studied, and the composition, structure and properties of the phosphate-bonded investments were obtained. Methods By means of XRD and SEM the composition and structure of the investments were obtained. The apparent porosity, bulk density, compression strength, setting expansion and thermal expansion of investments were tested for physical properties. Results By means of XRD it was found that phosphate-bonded investments consisted essentially of two main groups of ingredients, fillers and binders. The' fillers usually consisted of quartz and cristobalite. The binders were essentially basic MgO and NH4H2PO4. Under SEM, the investment was made up of coarse particles and fine powder, aggregate distributed equally into matrix, which is tightly interwoven by a lot of NH4MgPO4.6H2O crystals of needle or cylinder. Conclusion The physical properties of the phosphate-bonded investments were closely related to their composition and structure.