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X-ray diffraction techniques were performed to determine the actual crystal structure of A2 austenitic stainless steel (ASS) as-cast and A2 ASS after arc plasma sintering (APS) for 2 s. Computations were conducted on the basis of the Bragg arithmetic formula by comparing the S 2 arithmetic with the interplanar spacing. The Bragg arithmetic formula is a simple series for the determination of the crystalline phase of materials based on the Miller indices of cubic shapes or other shapes. A2 ASS as-cast was identified to have a crystal structure of face-centered cubic with lattice parameter a = 3.58 Å. A similar crystal structure can still be detected in A2 ASS after APS for 2 s with lattice parameter a = 3.60 Å. This finding was confirmed by neutron diffraction measurements and optical-electron microscopy observations. Under the same conditions, both A2 ASS as-cast and A2 ASS after APS for 2 s have similar cast structures. The grain boundary formed in A2 ASS as-cast is thinner than that in A2 ASS after APS for 2 s, which is visible in its boundaries. Moreover, the grain structure of A2 ASS after APS for 2 s, which was originally elongated particles, became globular particles. Similarly, granular precipitates became concentrated and encompassed the steel matrix along the grain boundaries. Furthermore, scanning electron microscopy with energy-dispersive X-ray analysis showed that particles and islands in steel are distributed in the grains and at the grain boundaries, respectively. Precipitates are composed of C, Cr, Fe, and Ni. The elemental contents of Cr and C are dominant; thus, Cr23C6 precipitate is formed at the grain boundaries. AbstrakPengaruh Sintering Arc-Plasma pada Sifat Mikro dan Struktur Baja Tahan Karat Austenitik Fe-Cr-Ni. Dalam penelitian ini, teknik difraksi sinar-X dilakukan untuk mengetahui bentuk struktur kristal dan parameter kisi sebenarnya baja nirkarat austenitik (ASS) A2 as-cast dan A2-ASS yang disinter plasma selama 2 detik. Perhitungan dilakukan dengan menggunakan dasar rumus Bragg, dengan membandingkan nilai S-aritmatika dan jarak antarplanar. Aritmatika Bragg adalah rangkaian sederhana dari penentuan kristal suatu bahan berdasarkan bentuk kubik Indeks Miller atau lainnya. ASS teridentifikasi memiliki struktur kristal face centered cubic (FCC) dengan parameter kisi a = 3,58 Å. Struktur kristal yang serupa masih ditemukan di ASS setelah arc plasma sintering (APS) selama 2 detik dengan parameter kisi a = 3,60 Å. Hasilnya dikonfirmasi dengan pengukuran difraksi neutron dan pengamatan struktur mikro menggunakan Mikroskop Optik (MO) dan Elektron (SEM). Dengan asumsi kondisi yang sama saat proses pengecoran, kedua ASS A2 memiliki struktur cor yang sama, batas butir yang dibentuk dalam ASS A2 as-cast lebih tipis daripada batas butir dalam ASS A2 setelah APS selama 2 detik yang cenderung sangat terlihat sangat jelas batas-batasnya. Sementara, pola butiran dalam A2 ASS setelah APS selama 2 detik, partikel yang awalnya memanjang berubah menjadi partikel globular pada struktur butir. Demikian juga, e...

This study aimed to determine the tensile strength and strain properties of poly(methyl methacrylate) (PMMA)/nano-zircon (n-ZrSiO4) composites with various nano-zircon sizes. Wet milling method for 5 and 15 h without annealing treatment was used to obtain the nano-zircon powders. Results showed that milling for 15 hours can reduce zircon size up to 93 nm. Meanwhile, the composites were synthesized with zircon compositions of 1, 2.5, and 5 wt.%. Dynamic Mechanical Analyzer (DMA) measurement were carried out to characterize the tensile-strain dependence on filler compositions of the PMMA/n-ZrSiO4 composites. The PMMA/n-ZrSiO4 composite with 5 wt.% and 15h milling zircon exhibited the highest tensile strength, ca. 10.02 MPa or 2 times of the pure PMMA. The tensile strength of the composites can be explained from the mean size and size distribution of the filler.

The thermomechanical and optical properties of poly(methyl methacrylate) (PMMA)/quartz and PMMA/zircon composites at filler content variations of 0, 1, 2.5, and 5 wt% have been studied. The silica quartz and zircon powders were derived from local sands collected from Tanah Laut, South Kalimantan, and Kereng Pangi, Central Kalimantan, Indonesia, respectively. The nanoquartz and nanozircon fillers (herewith were designated as quartz and zircon respectively) were obtained by milling these powders for 15 h. Dynamic mechanical analysis was used to acquire the storage modulus and glass transition temperature as the thermomechanical properties of the PMMA/quartz and PMMA/zircon composites. Meanwhile, the optical properties were determine using ultraviolet–visible spectroscopy. Results indicate that zircon fillers can improve the storage modulus of the composites up to 1.85 times that of PMMA alone. Zircon is more effective than silica in improving the storage modulus of PMMA. Implementing the degradation rate model shows us that all the composites have nearly the same degradation behavior in the glassy region. Moreover, the addition of fillers decreases the band gap energies.

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