1. Gypsum powder for grouting
陶瓷消费中注浆成形的瓷种（种类）较多。日用陶瓷大件异型件、卫生陶瓷、理化瓷、陶瓷烧成用的一些窑具等都采用注浆成形消费。注浆成形主要请求石膏模型的吸水性能。普通采用普通β石膏粉或局部采用α与β按比例混合的石膏粉，细度普通为80目～120目。石膏和水的比例普通在(1.2～1.46):1。依据瓷种和消费工艺的不同，石膏和水的比例有所区别。例如日用陶瓷和理化瓷的小件注浆消费中，由于是常压成形且体积较小，对模型强度请求不高，主要强调模型的吸水性，故石膏和水的比例普通在1.2:1左右。这种模型的吸水率普通为45%～50%，干抗折强度在2.8～3.5Mpa 。而卫生陶瓷微压注浆成形消费和日用陶瓷的压力注浆消费中，普通体积较大，除了主要强调模型吸水性之外，还对模型的强度提出严厉的请求，故石膏和水的比例请求大些，普通在(1.35～1.5):1。这种模型的吸水率普通在35%～42%，干抗折强度在 3.8～4.5 Mpa。
There are many kinds of grouting ceramics in ceramic consumption. Grouting is used to form large abnormal parts of domestic ceramics, sanitary ceramics, physical and chemical ceramics, and some kilns for firing ceramics. The water absorption of gypsum model is the main requirement of grouting forming. Ordinary use of ordinary beta gypsum powder or local use of a and beta proportionally mixed gypsum powder, the fineness of ordinary 80 mesh to 120 mesh. The ratio of gypsum to water is (1.2-1.46): 1. The proportion of gypsum to water varies according to the type of porcelain and the consumption process. For example, in grouting consumption of daily-used ceramics and physicochemical ceramics, the ratio of gypsum to water is generally about 1.2:1, because of its atmospheric pressure forming and small volume and low requirement for model strength, which mainly emphasizes the water absorption of the model. The water absorption of this model is generally 45%-50%, and the dry flexural strength is 2.8-3.5 Mpa. In the consumption of micro-pressure grouting for sanitary ceramics and the consumption of pressure grouting for daily ceramics, the general volume is larger. Besides emphasizing the water absorption of the model, strict requests are also made for the strength of the model. Therefore, the ratio of gypsum to water is larger, generally in (1.35-1.5): 1. The water absorption of this model is generally 35%-42%, and the dry flexural strength is 3.8-4.5 Mpa.
2. Gypsum Powder for Rolling Forming
Rolling forming is the main forming method of domestic ceramics. It mainly emphasizes the strength of the model, so that the model can accept more intense wear resistance and impact resistance. At the same time, it also requests that the model has certain water absorption and high temperature resistance. The main gypsum powder used is high strength alpha gypsum powder. The ratio of gypsum to water is (1.6-1.8): 1, and the water absorption of the model is 27-31%. In order to ensure the strength and avoid deformation of the model, the proportion of plaster powder to water can be fine-tuned according to the different consumption factories of plaster powder, the volume of products and the forming process of Yin-Yang die. The proportion of plaster powder to water is smaller than that of ordinary volume, which is (1.6-1.7): 1; the proportion of large volume is higher, which is (1.7-1.8): 1, or even higher. When it reaches 2.0:1, the water absorption of the model is 22%-23%.
3. Gypsum Powder for Plastic Compression Forming
Plastic compression forming is a special forming process for daily-use ceramics, also known as cold plastic compression forming. It is developed with more and more special-shaped and large parts in daily-use ceramics industry. It is especially suitable for large and special-shaped parts with relief patterns. As for the types of rolling forming that can not be consumed, besides grouting, this plastic forming process is adopted. The gypsum powder used is also high strength alpha gypsum powder. The ratio of gypsum to water is generally used in (1.6-1.8): 1. The water absorption rate of the model is usually 27-31%. It mainly emphasizes the strength, wear resistance and low shrinkage coefficient of the model. At the same time, it requests that the model has certain water absorption and air permeability.
4. Gypsum powder for mother mould
Also known as resin gypsum or K-type powder, the general fineness of 250-300 mesh. It participates in special chemical additives in alpha gypsum powder, or adopts special technology in the process of alpha gypsum stir-frying, which improves the structural properties of high strength alpha gypsum powder and forms special high strength gypsum powder. This kind of gypsum powder does not request water absorption, mainly requests high strength, high hardness, low shrinkage and high lubricity and brightness of the tire appearance. The standard consistency of this kind of gypsum powder is very low. The ratio of gypsum to water in consumption can reach (2.3-2.85): 1. It can be stirred for 10-15 minutes without solidification, and its dry flexural strength can reach 11.5 Mpa. Practical consumption experience shows that the activity and condensation performance of gypsum paste are still good at such a high proportion, the process operation can still stop smoothly, and the shrinkage rate of gypsum is very small. But the need to note that the gypsum in such a high proportion, the initial setting, the final setting distance of the time is too short (only about 1 minute), once the initial setting time, will immediately solidify, especially in operation.
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