ゼラチン製造の副生物としての燐酸水素カルシウムを利用した磁器素地の焼成反応過程
1976 年 84 巻 968 号 p. 185-193
詳細
1976 年 84 巻 968 号 p. 185-193
The development of a new type of china very similar to bone china has been successfully secured by utilizing bone phosphate, a by-product of gelatin production, instead of using bone ash (calcined cow bone) as a characteristic raw material of the china. The fundamental study on the reaction process during firing this type of china was described in the present paper.
CaHPO4⋅2H2O as the major constituent of bone phosphate causes the reactions mentioned below when the green body was fired at temperatures over 1000°C, which is discriminated from the behavior of 3Ca3 (PO4)2⋅Ca(OH)2 as the major constituent of bone ash.
1) Bone phosphate releases a part of P2O5-component and makes it diffuse into the decomposed kaolinite and sericite, the whilst the former is transformed into β-Ca3(PO4)2.
2) The P2O5-component which has diffused into the decomposition product of kaolinite or sericite facilitates the melting and promotes the sintering of the body.
3) Along with the melting of feldspar, the other part of P2O5-component released from bone phosphate diffuses into the melt of feldspar, while the bone phosphate is transformed into β-Ca3(PO4)2.
From the results of various observations and measurements for the reactions mentioned above, it was secured that such a china body made in use of bone phosphate is successfully fired at a temperature lower by 100 to 200°C than the firing temperature for the conventional bone china and that the fired body consists of β-Ca3(PO4)2 and glass. This is distinguishable from the traditional bone china made in use of bone ash which is known to consist of β-Ca3(PO4)2, anorthite and glass.
The transverse strength of the china body was found to increase with progressing vitrification and with increasing elasticity due to densification resulting from viscous flow of the glassy matter formed during firing.
