6. Influence of some technological factors on creep property
The microstructure of refractories is determined by the production process. The size and distribution of porosity, the bonding strength between the binder and clinker particles, and the development and contact of crystals are all formed in the production process.
① When the number of binder phase increases from 15% to 45%, the material density increases and the number of macropores decreases. When the content of binding phase is 5%, the aggregate particles are in direct contact with each other. Because the amount of binder is not enough to fill the gap, the contact area is small, resulting in large local stress and increased creep.
The change of the critical particle size of the aggregate has no significant impact on the creep. The reasonable particle grading can form a compact stack, which will reduce the porosity and creep of the sample.
② As mentioned before, the atmosphere has a great influence on creep. Therefore, the appropriate atmosphere should be selected according to different materials, and the oxidation atmosphere should be selected for Al2O3-SiO2 system materials. In addition, the structure of materials depends on the structural conditions reached after high-temperature sintering. Therefore, it is required to adopt appropriate temperature system, pressure system, holding time and sintering atmosphere to fully sinter the materials and make good contact between crystals, thus reducing the creep rate
In a word, the creep property of refractories depends on the porosity, phase composition and the development of contact between particles.
Among all phases in refractories, glass phase plays a role in creep, and the viscosity of glass phase has a greater impact.