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In this paper, we present and discuss experimental results from a microwave sintering of silica glass-ceramics, produced from amorphous silica xerogel extracted from sago waste ash. As a radiation source for a microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of the amorphous silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1200°C. Microwave absorbing properties of the sintered samples were investigated by measuring the dielectric constant, the dielectric loss, and the reflection loss at different frequencies in the interval from 8.2 to 12.4 GHz. Furthermore, the characteristics of the formation process for producing silica glassceramics were studied using a Raman Spectroscopy and a Scanning Electron Microscopy (SEM). The results indicate that the samples sintered at 1200°C are characterized by lower reflection losses and a better transparency due to the formation of a fully crystallized silica glass-ceramic at sufficiently high temperature.

Implan gigis based on metal still has weaknesses. New development is currently developed with the surface modification of multilayer coatings Ti-Al-Cr and hydroxyapatite on calcium phosphate cement (CPC) for Implan gigi application. Objective: To analize the thickness of multilayer coating alloy Ti-Al-Cr and hydroxyapatite on CPC synthesis by sol-gel method. Methods: Scanning electron microscopy (SEM) was conducted to analyze the thickness and morphology of microstructure layer formed on CPC. Result: SEM showed that coating Ti-Al-Cr on CPC successfully formed 1µm of thickness and showed 10µm of hydroxyapatite. Conclusion: The innovation of modification surface multilayer coatings Ti-Al-Cr and hydroxyapatite on CPC was successfully done by sol-gel method with a variety thickness. ABSTRAKModifikasi permukaan pada semen kalsium fosfat dengan multilapis Ti-Al-Cr dan hidroksiapatit dengan metode sol-gel. Implan gigi berbahan dasar logam paduan titanium Ti-Al-Cr dilapisi hidroksiapatit diketahui masih memiliki kelemahan. Oleh karena itu dilakukan pengembangan dengan modifikasi permukaan dengan multilapis Ti-Al-Cr dan hidroksiapatit pada semen kalsium fosfat untuk aplikasi implan dental. Tujuan: Penelitian ini bertujuan untuk melihat ketebalan multilapis logam paduan Ti-Al-Cr dan hidroksiapatit pada CPC dengan sintesis metode sol-gel. Metode: Analisis ketebalan multilapis dan mikrostruktur logam paduan Ti-Al-Cr dan hidroksiapatit pada CPC dilakukan dengan menggunakan Scanning Electron Microscopy (SEM). Hasil: SEM menunjukkan lapisan logam paduan Ti-Al-Cr pada CPC berhasil dibentuk dengan ketebalan 1µm sedangkan lapisan hidroksiapatit yang terbentuk adalah 10µm. Simpulan: Modifikasi permukaan dengan multilapis Ti-Al-Cr dan hidroksiapatit pada CPC berhasil dilakukan dengan menggunakan metode sol-gel dengan ketebalan bervariasi.