Papers by Keyword: Titanium Diboride

Abstract: Thermally sprayed NiCrBSi alloys have attracted interest in various fields of protective coating applications due to their good properties, especially for wear and corrosion resistance. Titanium diboride (TiB₂) is an attractive additive particle because of its properties such as high hardness, high melting point, high chemical resistance, high elastic modulus and low density. In this work, the effect of TiB₂ on dry reciprocating wear behavior of NiCrBSi-TiB₂ coating was systematically studied. NiCrBSi alloy powder was mixed with 15, 20, and 25 wt.% TiB₂ powder. Subsequently, mixed powder was coated on the substrate of 316L stainless steel (∅20 mm and 5 mm thickness) by High Velocity Oxygen Fuel (HVOF) technique. The microstructure of the coating was investigated under an optical microscope and scanning electron microscope (SEM). The hardness of the coating was measured by microhardness. In addition, dry sliding friction and wear behavior of coating were performed on a reciprocating ball-on-flat wear tester machine. The high-chromium steel (AISI 52100) ball of 6 mm in diameter was used as the counterpart. The conditions of the tests were 8 mm in stroke, 1 and 2 Hz in testing frequency with 10 N load, and sliding distance of 100 m. The variation of friction coefficient was recorded during the tests. The results indicated that an increase in TiB₂ content within the coating led to the formation of dark gray phases, oxidation layers and porosities in the microstructure. Consequently, reduction in the coating's hardness and wear resistance were discovered. In addition, the addition of TiB₂ in the NiCrBSi coating resulted in the higher material loss on the counterface ball due to abrasive wear mechanism.

Abstract: The present work reported a novel way of making nanocrystalline Ti-B phases (titanium boride and titanium diboride) in a hypersonic plasma jet. According to the purpose to synthesize nanosized Ti-B phases, experiments with different mass proportions of precursors were implemented. The optimal ratio of precursors, which leads to the yield of titanium diboride is 93.2% and the average particle size, doesn`t exceed 56.1 nm, is the ratio of Ti: B of 26.7: 73.3.

Abstract: Aluminum-silicon (Al-Si) alloys are an important class of materials, alloys which have great interested in wide industries whether in light or heavy industries, due to their superior properties like high strength to weight ratio, corrosion resistance, and excellent castability. The mechanical strength and the effect of modifying alloys have been studied. To evaluate the strength and revealed the structural of these alloys, the Instron tensile and Shimidzu Vickers hardness tester have been employed while the fracture surfaces have been observed by Scanning electron microscope (SEM). From results obtained, the microstructure of Al-Si with TiB₂ has much finer microstructure compared to unfine Al-Si alloy. It showed that the eutectic silicon microstructure in Al-Si alloy changed from needles-look or acicular to fine grain size or globular when the added of TiB₂. The mechanical studies showed that the ductility of Al-Si alloy was much lower in the absence of grain refiner, TiB₂. The tensile strength of unrefined Al-Si and Al-Si with 6 wt.%TiB₂ as grain refinement were recorded 275 and 312 MPa respectively. The hardness value for the unrefined Al-Si alloy also shows less compared with Al-Si with grain refiner, 6 wt.%TiB₂, which are 74 and 78 MPa. This showed the results were significant improvements in mechanical properties have been obtained with the use of TiB₂ as grain refiner to Al-Si alloy.

Abstract: A wear-resistant composite coating process with electroslag surfacing using a current-supplying solidification mould was developed. The structure and properties of coatings from flux-cored wire deposited alloys with refractory micro-particles of titanium diboride, TiB₂, and nano-sized particles of titanium carbonitride, TiCN, were studied. Special features of the elasto-plastic deformation of composite alloys’constituents were studied with sclerometry.

Abstract: Aluminium based in-situ metal matrix composites (MMCs) have better properties and performance when compared to ex-situ MMCs. In this research, aluminium-copper (Al-Cu) alloy was reinforced with 1 to 6wt.% titanium diboride (TiB₂). Al-MMCs has been fabricated with salt route reaction process at 800 °C via potassium hexafluorotitanate (K₂TiF₆) and potassium tetrafluoroborate (KBF₄) salts. Al-Cu composites reinforced with 1,2, 3 and 6wt.% TiB₂ then will be characterized their mechanical properties and microstructure. From results obtained, increased TiB₂ contents will increased the value of tensile and hardness properties of Al-Cu alloy. The composites synthesized using in-situ techniques exhibit the presence a uniform distribution of reinforcement that tends to be fine and associated with a clean interface with the metallic matrix. In order to achieve a good mechanical and wear properties it is important to control Al₃Ti phase formation during the synthesis of in situ Al-Cu/TiB₂ composites.

Abstract: The data of the study of the elemental and phase composition, the condition of the defect substructure, mechanical and tribological characteristics of titanium alloy VT6 subjected to electroexplosive carburization with a sample of titanium diboride powder and the subsequent treatment by high-intensity pulsed electron beam is presented. It has been established that the main mechanisms responsible for an increase in the mechanical and tribological properties of the material are solid, dispersion, and grain boundary.

Abstract: The effect of nickel contents and milling parameters on the preparation procession of TiB₂-Al₂O₃ composite powders during the mechanical alloying (MA) was studied in this paper. Milling parameters have certain influence on the phase transformation of Ni-Al-TiO₂-B₂O₃ system during mechanical processing. With the same milling parameters, the proper content of Ni can promote the reaction route and influence the microtopography of the products.

Abstract: The main goal of this work is to study dry sliding wear behavior of NiCrSiB-TiB₂ plasma sprayed coating against NiCrSiB coating. NiCrSiB-based powders with 10, 20, 40 wt.% TiB₂ particles content were deposited on steel substrates by plasma spraying. The structure of NiCrSiB-TiB₂ coatings consists of Ni-based matrix and TiB₂ and CrB grains. Among the coatings studied, the NiCrSiB-20wt.%TiB₂ shows excellent wear-resistance. The worn surfaces were observed using scanning electron microscopy and Auger electron spectroscopy to determine the wear mechanisms.

Abstract: SiC-TiB₂/B₄C composites were fabricated by hot-press sintering B₄C with silicon powder and tetrabutyl titanate (precursor of TiO₂) as sintering and reinforcement agents. The influence of additives on hot-press sintering densification, microstructure and properties of composites were studied. The results showed that TiB₂ and SiC generated by chemical reaction between additives and B₄C matrix reinforced the sintering activity of the mixed powders and accelerated significantly the hot-press sintering densification rate of B₄C from 1200 °C to 1700 °C. According to the SEM observation, the second phase of TiB₂ and SiC particles synthetized in situ sited along the grain boundaries of B₄C, meanwhile, those SiC particles of nanoscale size embedded into the B₄C grains, and thereby, intra/inter-type ceramics formed. The maximum relative density of 98.1% was obtained with 9wt.% TiO₂. The typical valus of Vickers hardness, bending strength and fracture toughness can reach 26.7 GPa, 580 MPa and 5.0 MPam^1/2, respectively.

Abstract: Possibility of getting the boron-containing composite materials at aluminum-thermal combustion of boron-containing systems in argon medium. The combustion took place in reactor (at up to 30 atm. argon pressure). Influence of argon pressure and aluminum content (in initial feed) on content of the solid (titanium diboride and aluminum oxide) phases in synthesis products.