Microstructural and technological investigation of bone China reformulated with nepheline syenite and quartz addition

Abstract

In this study, bone china body was reformulated by completely replacing Cornish stone with nepheline syenite and quartz. Effect of controlled milling/mixing on the technological properties and microstructural evolution was also studied. Specimens prepared both from reformulated and controlled milled/mixed bodies were sintered between 1200 and 1250°C with 25°C increment. Sintering and technological properties of reformulated bodies were not being adversely affected but conversely, the measured flexural strength values (55 MPa) were half of the value that was published for bone china (100 MPa). Microstructural investigations showed that enlarged pore formation was the reason for strength reduction. However, improvement in particle packing by controlled milling/mixing eliminated enlarged pore formation and in response, flexural strength values increased to conventionally quoted levels. Detailed microstructural investigations revealed that the reason behind enlarged pore formation was heterogeneous distributions of body components, especially CaO and quartz grains. It was suggested that variations of CaO and SiO 2 to form improper ratio between them would affect the viscosity of glassy phase and crystallization, which would prevent gases in pores to dissolve away. The obtainment of homogenous distribution of body components by controlled milling/mixing has a strong influence on the evolution of microstructure and improvement of technological properties.

Reformulation of bone china body for the reduction of pyroplastic deformation

“…As our previous study, the resulting slurry was conducted to the laser light diffraction particle size analysis (Malvern Mastersizer 2000). 25 We obtained similar particle size distributions under the controlled milling process having 24-rpm speed and 24-h duration for each batch (Figure 2). All milled bodies exhibited unimodal particle size distributions with a maximum point that represents an average particle size of about 3.8 μm.…”

“…5 But nowadays, other types of flux materials like nepheline syenite are also used due to the decrease of Cornish stone sources. 20,25 In this study, we used sodium and potassium feldspar as fluxing agents (purchased from Esan Eczacibasi Industrial Raw Materials Co., Turkey). Moreover, we used the synthetic bone powder (kindly supplied by Kale Minerals Co., Turkey), which is a good alternative to natural bone ash, to avoid environmental pollution and time-consuming preparation steps.…”

Kinetic study of the transformation of sodalite to nepheline

“…Nepheline (Na,K)AlSiO 4 is a feldspathoidal mineral, with great economical importance as a raw material in glass and ceramics manufacture. Thus, nepheline is used in the production of porcelain stoneware tiles, 1 bone china, 2 or composites for physicochemical purification of wastewater, 3 among others.…”

Determination of Ca3(PO4)2 in Bone China by Microwave Digestion-ICP-AES

“…Bone chinaware [1][2][3][4] is recognized as the world's most high-end daily-use porcelain. It is made by adding herbivore bone meal as raw material to china clay and firing it in a phosphate system using calcium phosphate as a solvent.…”