资源描述：
玻璃 Specific volume（比容）one of the distinctions between crystalline and noncrystalline materials lies in the dependence of specific volume Viscosity（粘度）Upon cooling，a glass becomes more and more viscous（粘稠的）in a continuous manner with decreasing temperature； There is no definite temperature at which the liquid transs to a solid as with crystalline materials. fictive temperature，Tg （玻璃化转变温度） A slight decrease in slope of the curve occurs at what is called the glass transition temperature, or fictive temperature，Tg . Below this temperature, the material is considered to be a glass; above, it is first a supercooled liquid（过冷液体）and finally a liquid. Most glass-ing operations are carried out within the working rangebetween the working and softening temperatures. 加工步骤 Four different ing s are used to fabricate加工 glass products （1）pressing，（2）blowing， （3）drawing，Drawing is used to long glass pieces such as sheet，rod，tubing，and fibers，which have a constant cross section. （4）fiber ing. Glass Tempering（回火） （1）Definition The strength of a glass piece may be enhanced by intentionally inducing compressive residual surface stresses. This can be accomplished by a heat treatment procedure called thermal tempering. （2）Environment With this technique， the glassware is heated to a temperature above the glass transition region yet below the softening point. It is then cooled to room temperature in a jet of air， or in some cases， an oil bath. The residual stresses arise from differences in cooling rates for surface and interior regions. Processing（回火加工） Initially，the surface cools more rapidly and， once having dropped to a temperature below the strain point，becomes rigid. At this time，the interior，having cooled less rapidly， is at a higher temperature above the strain point and，therefore，is still plastic. With continued cooling， the interior attempts to contract to a greater degree than the now rigid exterior will allow. Thus， the inside tends to draw in the outside， or to impose inward radial stresses. After the glass piece has cooled to room temperature， it sustains compressive stresses on the surface， with tensile stresses at interior regions. The characteristics of clay（粘土） 1 Hydroplasticity（含水塑性） when water is added，they become very plastic，a condition termed hydroplasticity. 2 Fusion temperature range clay fuses or melts over a range of temperatures；thus，a dense and strong ceramic piece may be produced during firing without complete melting such that the desired shape is maintained. This fusion temperature range，of course，depends on the composition of the clay. 3）Composites Clays are aluminosilicates（铝硅酸盐），being composed of alumina Al2O3 and silica SiO2，that contain chemically bound water. They have a broad range of physical characteristics，chemical compositions，and structures； common impurities include compounds usually oxides of barium，calcium，sodium，potassium（钾），and iron， and also some organic matter. 4 Structure Crystal structures for the clay minerals are relatively complicated； however，one prevailing characteristic is a layered structure. The most common clay minerals that are of interest have what is called the kaolinite（高岭石） structure. Kaolinite clay [Al2Si2O5OH4] ,When water is added，the water molecules fit in between these layered sheets and a thin film around the clay particles. The particles are thus free to move over one another，which accounts for the resulting plasticity of the water–clay mixture. Fabrication of Clay Products techniques are utilized for ing clay-based compositions hydroplastic ing（含水塑性成型） and slip casting（浇铸法）
展开阅读全文
