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Effect of Boron Sinter-Aid on the Microstructure and Properties of Austenitic Stainless Steel- TIB2 Composites

Sulima I., Jaworska L., Karwan-Baczewska J.

Archives of Metallurgy and Materials

2015

Vol. 60, iss. 4

2619--2624

In the work, the effect the boron addition on the microstructure and properties of the composites with austenitic steel of matrix was investigated. The composites were consolidated using the high pressure-high temperature (HP-HT) method. Two composite types were fabricated, i.e. steel with 8 vol.% TiB2 and steel with 8 vol.% TiB2 and 1 vol.% boron. Density of sintered materials was measured according to the Archimedes principle. Mechanical properties were determined by Vickers microhardness and compression test. The wear resistance was investigeted using ball-on-disc method. The microstructure of composites was analyzed using a scanning electron microscope. The results show that the boron addition and sintering parameters have influence on the mechanical and tribological properties of the composites. Materials are characterized by very high density. The composites with boron exhibited higher Young’s modulus and microhardness in comparison with the properties of composites without boron addition.

W pracy przedstawiono wyniki badań dotyczące wpływu dodatku boru na mikrostrukturę oraz właściwości kompozytów o osnowie stali austenitycznej. Do wytworzenia kompozytów zastosowano spiekanie wysokociśnieniowe. Wytworzono dwa wartianty kompozytu: stal z 8%obj. TiB2 oraz stal z 8%obj. TiB2 +1% obj. boru. Po procesie spiekaniu określono gęstość pozorną, moduł Younga, mikrotwardość Vickersa oraz wytrzymałość na ściskanie spiekanych kompozytów. Odporność na ścieranie określono stosując metodę ball-on–disc. Badania mikrostruktury przeprowadzono za pomocą skaningowej mikroskopii elektronowej (SEM). Otrzymane wyniki wykazały, że dodatek boru oraz warunki spiekania mają wpływ na właściwości mechaniczne oraz tribologiczne kompozytów. Wszystkie spiekane materiały charakteryzowały się bardzo wysoką gestością. Kompozyty modyfikowane borem wykazują wyższy moduł Younga oraz mikrotwardość.

Sintering of diamond composites with SHS-prepared bonding phases

Putyra P., Jaworska L., Stobierski L., Morgiel J, Bućko M., Rozmus M., Wyżga P.

Journal of Achievements in Materials and Manufacturing Engineering

2013

Vol. 61, nr 2

268--273

Purpose: The aim of this study was to investigate materials with reduced cobalt content as well as diamond compacts with non-cobalt bounding phase. Design/methodology/approach: Phases Ti3SiC2 and Cr3AlC obtained using the self-propagating High-Temperature Synthesis (SHS) technique were used as a PCD (polycrystalline diamond) bonding phases. Diamond composites with 10-20 mass% of SHS bonding phase were prepared by using a Bridgmann-type High Pressure - High Temperature (HP-HT) apparatus. Sintering of the composites were carried out at 1950±50°C and 8±0.2 GPa. Phase compositions of MAX powders and compacts were tested using X-ray diffraction. Microstructure investigations were performed using scanning (JEOL) and transmission (Tecnai FEG 200kV) microscopes and high spation resolution EDS mapping. Findings: During the sintering processes, bonding phase decomposition processes occur in the material. Mainly carbides and silicides are formed. Diamond phase materials are characterized by multi-phase composition. Research limitations/implications: Future research in the field of reduced cobalt content composites and cobalt replaced by bonding phase with Cr2AlC should focus on reduction of the graphite which affects on lower composite hardness. Such materials require an improvement in stress deposition. Originality/value: Due to the low thermal stability of the cobalt as a bonding phase in PCD there is a need to reduce its volume in the composite. Application of the newest non-cobalt bonding phases (Ti3SiC2 and Cr3AlC) obtained by SHS sythesis.