การประชุมวิชาการระดับชาติ ครั้งที่ 16
มหาวิทยาลัยราชภัฏนครปฐม

     The aims of this research, Study the effect of using ashes from coconut shell to develop imitation black spinel. From the analysis of main components of coconut shell, before and after sintering. It was found that before sintering coconut shells K₂O SiO₂ and CaO were the main elements. The proportions were equal to 67.54, 13.12 and 14.51 (Wt%) and also found that the elements of the additives that affect the color Including MnO, Fe₂O₃ and CuO. After sintering at higher temperatures (400, 600, 800, 1000 °C). It was found that the amount of K₂O and CaO decreased. On the other hand, the amount of SiO₂ that increased with increasing sintering temperature. Then use the coconut shell ashes to replace the chemicals SiO₂, K₂O and CaO in the glass formula (55-x)B₂O₃ : 10SiO₂ : 15K₂O : 5CaO : 15Bi₂O₃ : xCoO where x was concentration of CoO (8, 10, 12, 14 and 16 mol%). Found that the glass is opaque. The density of the glass was between 4.1337 ± 0.0002 to 4.1600 ± 0.0001 g/cm³, which is greater than the density of black spinel. Glass has a hardness value between 6.5 -7.5 Mohs scale. This hardness value is equal to real black spinel.