Normal consistency of gypsum powder

　　也稱為標(biāo)準(zhǔn)水或標(biāo)準(zhǔn)混合水。為100份半水石膏粉獲得標(biāo)準(zhǔn)流動(dòng)性(試樣直徑:200±5mm)所需要的加水量，以百分?jǐn)?shù)表示。半水石膏粉性能是描述半水石膏粉性能的重要指標(biāo)，是比較石膏粉質(zhì)量和描述半水石膏粉其他性能指標(biāo)的基礎(chǔ)(半水石膏粉性能應(yīng)在相同濃度下進(jìn)行比較)。然而，這一指標(biāo)并不是我們?cè)诖笠?guī)模生產(chǎn)中模擬的混合水量，而是實(shí)際情況大于它。半水石膏的標(biāo)準(zhǔn)稠度較小，一般在45% ~ 55%之間，而半水石膏的標(biāo)準(zhǔn)稠度較大，一般在70% ~ 80%之間。通過(guò)對(duì)半水石膏粉標(biāo)準(zhǔn)稠度的測(cè)試，可以初步判別石膏粉的結(jié)晶型(型)，判斷石膏粉的質(zhì)量。

　　Also known as standard water or standard mixed water. The amount of water needed to obtain the standard fluidity (sample diameter: 200 + 5mm) for 100 parts of semi-aqueous gypsum powder is expressed in percentage. The performance of hemihydrate gypsum powder is an important index for describing the performance of hemihydrate gypsum powder. It is the basis for comparing the quality of hemihydrate gypsum powder and other performance indexes of hemihydrate gypsum powder (the performance of hemihydrate gypsum powder should be compared at the same concentration). However, this indicator is not the amount of mixed water we simulate in large-scale production, but the actual situation is larger than it. The standard consistency of hemihydrate gypsum is relatively low, generally between 45% and 55%, while that of hemihydrate gypsum is relatively high, generally between 70% and 80%. By testing the standard consistency of hemihydrate gypsum powder, the crystalline type and quality of gypsum powder can be judged preliminarily.

　　石膏細(xì)度

　　Gypsum fineness

　　半水石膏粉是表征石膏粉性能的重要指標(biāo)。它與半水石膏在水中的凝結(jié)速率、模型的強(qiáng)度、表面硬度和光潔度有關(guān)。測(cè)定細(xì)度的方法包括篩數(shù)(篩渣百分比)、顆粒級(jí)配和比表面積。一般來(lái)說(shuō)，石膏粉的細(xì)度越細(xì)，其顆粒的比表面積越大，與水的接觸面積越大，在水中的溶解速度越快。與水結(jié)合后反應(yīng)充分，石膏漿凝結(jié)速度越快，形成網(wǎng)狀結(jié)構(gòu)，模型強(qiáng)度較高，但吸水率相應(yīng)降低。石膏粉細(xì)度粗，一般在80 ~ 90目，模型強(qiáng)度低;Alpha石膏細(xì)度較好，一般在120 - 180目之間，模型強(qiáng)度較高。目前，國(guó)內(nèi)陶瓷生產(chǎn)中使用的石膏粉一般為100 ~ 120目，高不超過(guò)180目。國(guó)外采用的石膏粉細(xì)度為180 ~ 250目。

　　Hemihydrate gypsum powder is an important index to characterize the performance of gypsum powder. It is related to the coagulation rate of hemihydrate gypsum in water, the strength of the model, the surface hardness and the smoothness of the model. The methods for determining fineness include sieve number (percentage of sieve residue), particle size distribution and specific surface area. Generally speaking, the finer the gypsum powder is, the larger the specific surface area of its particles, the larger the contact area with water, and the faster the dissolution rate in water. When combined with water, gypsum slurry reacts sufficiently. The faster the setting speed of gypsum slurry is, the network structure is formed. The strength of the model is higher, but the water absorption decreases accordingly. The fineness of gypsum powder is coarse, generally in 80 - 90 mesh, and the strength of model is low. Alpha gypsum has better fineness, generally in 120 - 180 mesh, and the strength of model is high. At present, gypsum powder used in domestic ceramic production is generally 100 - 120 meshes, up to 180 meshes. The fineness of gypsum powder used abroad is 180 - 250 meshes.