1. What are the stages of firing a bone china cup? What is the scope of each phase? How should the firing process be controlled?
Answer: It is mainly divided into preheating stage (normal temperature ~ 300. C), oxidative decomposition stage (300 ~ 950. C), high temperature stage (950. C ~ maximum firing temperature), high fire insulation stage, and cooling stage. Since there are many factors affecting the firing of ceramics, different firing systems should be determined according to specific conditions during operation, and the gas pressure in each part of the kiln should be controlled to a certain distribution through the equipment of the kiln to ensure the temperature system and atmosphere system. .
2. The function and conditions of low temperature and fast burning of bone china cup?
Answer: ①The role of low-temperature fast firing: saving energy and cost, making full use of raw material resources, improving the service life of kiln and kiln furniture, shortening the production cycle, and improving production efficiency.
②Conditions for fast firing at low temperature: the drying shrinkage and firing shrinkage of the blank glaze are small, the thermal expansion coefficient of the blank is small, and the change with temperature is close to a linear relationship. It is hoped that the thermal conductivity of the billet is good, and it is hoped that the billet contains a small amount of crystal transformation components. The fast-fired glaze requires strong chemical activity; reduce the water content of the billet entering the kiln, and increase the temperature of the billet entering the kiln; control the thickness, shape and size of the billet. ; Choose a kiln with small temperature difference and good heat preservation; choose kiln furniture with good thermal shock resistance.
3. Bone china manufacturers quickly fire bone china cup and plate products. The known firing temperature is 1150°C and the kiln exit temperature is 180°C. The water absorption rate is allowed to be between 3-10%. During production, the appearance quality and water absorption rate of the kiln products are good, and they are stacked in the warehouse for the next day’s inspection. However, 20-30% of the products are broken after inspection. Try to analyze What caused the product to break? and come up with a solution?
Answer: The reason for the cracking of the finished product may be the poor thermal stability of the ceramic plate and the expansion of moisture absorption. Since the water absorption rate of ceramic plate products is allowed to be between 3 and 10%, its water absorption rate is within the range of water absorption rate of stoneware, plus firing The temperature is low, and the temperature out of the kiln is relatively high, which easily makes the thermal stability of ceramic products poor and cracks.
4. What is the basis for setting the firing system for bone china cups?
Answer: ①The property change of the blank components during heating ②The size and shape of the product. ③Glaze firing method, including the mutual influence of the base glaze reaction during firing, and enter the cooling stage after the high-fire heat preservation is completed. ④ Kiln.
5. In order to shorten the firing cycle of ordinary bone china cups, it is planned to adopt rapid cooling at 600-400°C in the later stage of firing. Is it feasible? Why?
Answer: No, because at 573ºc, the quartz crystal form undergoes rapid conversion to a low-temperature type, and there is no liquid phase buffer, which is highly destructive and prone to deformation. If it is cooled rapidly at this stage, the product will break.
6. What are the requirements for the quality of blanks for rapid firing of bone china cups?
Answer:
① Drying shrinkage and firing shrinkage are both small.
② The thermal expansion coefficient of the billet should be small, and the change with temperature is close to a linear relationship, and it will not crack during the firing process.
③ The thermal conductivity of the billet should be good, so that the physical and chemical reactions can proceed rapidly during firing, and the thermal shock resistance of the billet can be improved.
④ It is hoped that the blank contains less crystal transformation components, so as to avoid damage to the blank due to volume changes.
7. What technological measures can be taken to achieve rapid firing?
Answer: The blank glaze can adapt to fast firing; reduce the water content of the blank entering the kiln, increase the temperature of the blank entering the kiln; control the thickness, shape and size of the blank; choose a kiln with small temperature difference and good thermal insulation performance; choose a kiln with good heat resistance kiln furniture.
8. The relationship between the formula of bone china cup blank, process factors, microstructure of porcelain body and properties of porcelain.
Answer: The chemical composition and process conditions of the blank will form different microstructures, and changes in the microstructure will affect the properties of the material.
9. How does the bone china cup process affect the physical and chemical properties of the product?
Answer: The technological process has a great influence on the physical and chemical properties of the product, because the technological process will affect the microstructure of the product and finally affect the performance of the product, so the technological process of ceramic production is very important to the performance of the product.
10. Briefly describe the reasons that affect the sintering of bone china cups.
Answer: There are many reasons that affect the sintering of bone china cups, mainly in the formula, the mineral composition of raw materials, the moisture content of the green body before entering the kiln, the firing atmosphere, and the firing temperature. The mineral composition of raw materials contains more volatile matter. And more gas is generated during high temperature reaction, which affects sintering. The firing atmosphere and firing temperature directly affect the sintering of the product. If the temperature is too low or too high, it will have a greater impact on the sintering temperature. If it is not reduced in time when it is reduced to flame, the reduction effect will not be achieved. If it is reduced in advance, the oxidation will be incomplete. The formulation affects the temperature and other conditions required for sintering to a certain extent.
Post time: Apr-26-2023