In China glass network 】 【 glass products in the process of forming and finalize the design the most significant is the viscoelasticity of glass (viscosity, surface tension and elastic properties) and thermal properties (heat conduction coefficient, specific heat, coefficient of thermal expansion, light transmittance of glass, radiation coefficient, heat transfer coefficient). Viscous flow of glass fluid movement and its mechanical properties in the plastic deformation process determines the glass fluid displacement characteristics of each particle under the action of external force, in the process of forming thermal resistance determines the heat transfer characteristics and strength, and with the cold medium.
Glass liquid viscosity with the increase of temperature drop and the characteristic is the basis of glass forming and finalize the design, it has a very important role in the process of glass molding, general sodium calcium silicate glass viscosity change rule: high temperature slowly, 1000-900 ° C growth, growing faster then the viscosity, can quickly finalize the design because the glass has any required viscosity value, so it can use various methods to shape.
2. Surface tension:
Glass liquid surface tension makes free glass liquid drop ball, this feature in the glass forming plays an extremely important role in the process, for example in the blow made type, due to the effect of surface tension, without forming dies can be made spherical glass bubble, the glass fiber and glass tube drawing heat can get round, in the cracking-off and baked, the surface tension can make the edge of circle, etc.
In most of the glass forming process, may have reached the temperature of the elastic works, at least in the products parts has been close to the temperature, therefore, temporary stress, these parts may occur if the stress is fast, glass is brittle fracture may occur, so, elasticity and eliminate the need for time, the elastic effects has become very important.
Iv. Thermal properties:
Glass its heat capacity, thermal conductivity, surface radiation and diathermancy of thermal properties will affect the glass molding cooling speed, the thermal conductivity of glass, surface radiation and heating properties, the greater the heat capacity is smaller, the faster the cooling rate of the glass.