SURFACE HARDENING PADA BAHAN STAINLESS STEEL 304 DENGAN ALAT RF-PLASMA NITROCARBURIZING

Surface hardening pada bahan Stainless Steel 304 dengan alat RF-plasma nitrocarburizing. Surface hardening pada bahan Stainless Steel 304 dengan alat RF-plasma nitrocarburizing telah dikerjakan. Beberapa samples telah di-nitrocarburizing pada temperatur 4000C selama (0,5-6) jam. Hasilnya menunjukkan bahwa, pada sample awal kekerasan bahan SUS 304 adalah 260,58 Kgf/mm2, setelah di-nitrocarburizing pada temperatur 400 0C selama 6 jam, kekerasannya menjadi 347,62 Kgf/mm2, sedangkan kedalaman maximum atom-atom nitrogen dan carbon yang terdifusi kedalam bahan SUS 304 ialah 109,1 micrometer. Pengamatan strukturmikro menunjukkan bahwa pada sample yang telah di nitrocarburizing pada temperatur 400 0C selama 6 jam terlihat jelas adanya lapisan atom-atom N dan C di dalam bahan SUS 304. Samples awal dan yang dinitrocarburizing pada 400 0C (t = 6 jam) terdapat matrix yang sama yaitu γ-phase, δ-ferrite, dan twinning transformation. Kata kunci : Nitrocarburizing, RF- plasma, SUS 304, kekerasan, struktur mikro   Surface hardening on stainless steel 304 material with RF-plasma nitrocarburizing. Surface hardening on stainless steel 304 material with RF-plasma nitrocarburizing made in BATAN have been carried out. Some samples was nitrocarburized at temperature 400 0C for (0,5-6) hour. The results show that the hardness of untreated sample of SUS 304 material was 260,58 Kgf/mm2, after the sample nitrocarburized at temperature 400 0C for 6 hour, the hardness increased up to 347,62 Kgf/mm2. Furthermore, the maximum depth of carbon and nitrogen atoms that diffused in SUS 304 was 109,1 micrometer. Microstructure observation shows that the sample after nitrocarburized at temperature 400 0C for 6 hour to be seen very clear that there are layer of N and C atoms in SUS304 material. Un-treated sample and sample that nitrocarburized at temperatur 400 0C (t = 6 jam) have same matrixes namely, γ-phase, δ-ferrite, and twinning transformation. Key words : Nitrocarburizing, RF- plasma, SUS304, hardness, microstructur

The Effect Of Ratio Of Gas Mixture For Mechanical Properties And Crystal Structures On 316l Stainless Steel Biomaterial Using Dc Sputtering Technique

316L stainless steel is widely used as an orthopedic implant due to its high corrosion resistance and biocompatibility, but the weakness of these materials is low hardness and high wear. The surface must be modified to improve the material. For the purpose, a titanium nitride (TiN) thin film was deposited on the surface of SS 316L using DC sputtering technique. The sputtering process was carried out for various of a gas mixture of argon (Ar) and nitrogen (N2) such as 90 Ar: 10N2, 80 Ar: 20 N2, 70 Ar: N2, and 60 Ar: 40 N2, while the other parameters kept constant. The objective of the gas mixture variation is to find out the optimum condition of ratio Ar: N2 gas mixture with the highest hardness and lowest wear resistance. From experiment done it's found that the highest hardness in order of 232.02 VHN, while before being coated the hardness is 133.61 VHN, or there is an increasing hardness by factor 1.73, while the wear resistance reduces from 11.6 × 10-8 mm2/kg to 1.17 × 10-8 mm2/kg or there is reducing in wear resistance by factor 9.9. The optimum conditions were achieved at Ar: N2 ratio = 70:30. From XRD analysis, it can be concluded that the crystal structure of TiN thin film is cubic with the peaks (111), (200), (202), (311) and (222). From cross-section microstructure analysis using Scanning Microscope Electron (SEM), it's found the thickness of the thin film is 744 nm