Refractory sintering
2018-02-06
For refractory materials, sintering is very important, whether it is natural raw materials, or synthetic raw materials, have to be burned, to sinter before use, fire-retardant refractory products is to achieve the date of sintering. Unshaped refractory materials in the process of gradually sintering.
From a process point of view, sinter is a sturdy, low porosity (almost airless 7L) stone made from a powder at high temperatures.
Refractories degree of flexibility of the signs, usually with the object size reduction (the so-called shrinkage), reduced porosity and bulk density increased to measure.
Sintering is mainly due to the strengthening of refractory material, the inevitable result of increased contact between the particles. Sintering (intrinsic) has the following processes: changes in the shape of the pore size phase; crystal growth, residual stress (suppression) reduction and equilibrium; liquid phase formation; redistribution of phase space; In many cases, sintering accompanied by multi-phase transformation of certain phases, solid-phase chemical reactions or liquid-phase reactions. The reaction forms a new phase and a solid melt.
The final cooling complicates the enumeration process, with some of the opposite processes occurring. Multi-product changes, melt crystallization and crystallization pressure may occur, the formation of the glass phase and other phenomena. Like the lower temperature drop, the refractory material produces stress and often produces macroscopic defects so that the refractory products are discarded. Temperature gradients, temperature change rates, phase and concentration gradients, atmospheres, high frequency field effects, vibrations and other conditions in a refractory body all depend on the temperature. Even within the refractory material. y1 its temperature changes have a very complex phenomenon, can not fully enumerate the occurrence of the process
