I agree with upstairs that the baseline is unstable. At first, I wanted to say whether CO2 was absorbed, but under the protection of inert gas, it should be impossible. Post basic attributes for future generations' reference. Chinese name: Hydroxyapatite English name: hydroxyapatite abbreviation: HAP molecular formula: Ca 10(PO4)6(OH)2 Molecular weight: 1004 Physical and chemical properties: melting point:1650 C, specific gravity: 3.16g. Ca/P: 1.67 crystal structure: hexagonal crystal product specifications: powder, porous particles, blocky (uncalibrated) products Application fields: bone replacement materials, plastic surgery, dentistry, chromatographic purification, calcium supplementation * The main components of teeth and bones * At present, it is widely used to manufacture cutting-edge new materials that meet the functional effects of teeth or bones: * healthy, bright and white * Tooth removal. Methods to prevent tooth decay and freshen breath: Ca(PO4)2 and CaCO3 react at high temperature according to the proposed ratio, at the same time, high-pressure steam is injected, and the powder is washed with NH4Cl aqueous solution and dried, which is divided into porous and dense types. The former is formed by foaming powder and sintering at 65438 0250℃, and the latter is formed by sintering at 65438 0250℃ after molding. Distribution: Widely distributed in human body and milk. In human body, it is mainly distributed in bones and teeth, and in milk, it is mainly distributed in casein colloidal particles and whey.