无机非专业英语 unit 6.pptVIP

Unit 6 Ceramic Fabrication Process: Conventional Routes to Ceramics 陶瓷生产工艺：陶瓷生产的常规途径 引言 1、Solid ceramic bodies are generally produced by using the process of powder compaction followed by firing at high temperature. 固体陶胚体通常都是利用粉末压实而后在高温烧结的工艺来生产。 Sintering or densification occurs during this heat treatment and is associated with joining together of particles, volume reduction, decrease in porosity and increase in grain size. 在这个热处理过程中发生烧结或者稠化现象，并且与颗粒靠拢、体积减少、气孔率减少以及晶粒长大密切相关。 The phase distribution or microstructure within the ceramic is developed during sintering and fabrication techniques used for shaping ceramics are described here. 在陶瓷中的相扩散或者微观结构在烧结中形成，成型陶瓷的制造技术在此也得以叙述。 The aim of these techniques is to produce microstructures suitable for particular applications. 这些技术旨在生产满足特殊应用的微观结构。 Precipitation from solution 溶液的沉淀析出 2、Alumina occurs as the mineral bauxite and is refined in the Bayer process whereby ore is initially dissolved under pressure in sodium hydroxide so that solid impurities (SiO2, TiO2, Fe203) separate from sodium aluminate solution. 氧化铝是以矿物质铝矾土的形式出现的，并且在精炼矾土工艺中得以精制。这个工艺借以矿石最初是在压力下溶解在氢氧化钠中的因此固体杂质如二氧化硅、二氧化钛、氧化铁等就可以从铝酸钠溶液中分离出来。 This solution is either seeded with gibbsite crystals (a-Al2O33H2O) or undergoes autoprecipitation to bayerite (β-Al2O33H2O) after its neutralisation with CO2 gas. 这种溶液要么是结晶出水铝矿晶体，要么是和二氧化碳气体中和后沉淀出三水铝石。 Temperature, alumina supersaturation and amount of seed affect particle size during crystallisation. 温度、氧化铝的过饱和以及晶籽的数量都会影响结晶过程中的颗粒大小。 3、Problems can arise when two or more components are coprecipitated. 当两个或者更多成分共沉淀时问题就出现了。 Thus, different species do not always deposit from solution at the reaction pH, while washing procedures can selectively remove a precipitated component as well as dissolve entrained electrolyte. 因为，在反应pH下，不同组分并不总是会从溶液中沉淀出来，虽然清洗过程可以有选择性的去除一种析出成分，同时溶解产生的电解质。 The difficulty in maintaining chemical homogeneity is serious as inhomogeneities have a deleterious effect on the mechanical and