Hot Sliding Wear of 88 wt.% TiB–Ti Composite from SHS Produced Powders

Abstract

Titanium alloys and composites are of great interest for a wide variety of industrial applications; however, most of them suffer from poor tribological performance, especially at elevated temperatures. In this study, spark plasma sintering was utilized to produce a fully dense and thermodynamically stable TiB–Ti composite with a high content of ceramic phase (88 wt.%) from self-propagating high temperature synthesized (SHS) powders of commercially available Ti and B. Microstructural examination, thermodynamic assessments, and XRD analysis revealed the in situ formation of titanium borides with a relatively broad grain size distribution and elongated shapes of different aspect ratio. The composite exhibits a considerable hardness of 1550 HV30 combined with a good indentation fracture toughness of 8.2 MPa·m1/2. Dry sliding wear tests were performed at room and elevated temperature (800 ℃) under 5 and 20 N sliding loads with the sliding speed of 0.1 m·s−1 and the sliding distance of 1000 m. A considerable decline in the coefficient of friction and wear rate was demonstrated at elevated temperature sliding. Apart from the protective nature of generated tribo-oxide layer, the development of lubricious boric acid on the surface of the composite was wholly responsible for this phenomenon. A high load bearing capacity of tribo-layer was demonstrated at 800 ℃ test.

High-Temperature Wear Performance of hBN-Added Ni-W Composites Produced from Combustion-Synthesized Powders

“…The system was designed to obtain Ni-W alloys with a molar composition ratio of Ni:W = 4:1. The thermodynamic design enabled evaluating the combustion temperature (T ad ) in adiabatic conditions and the equilibrium phase composition of combustion products in the multielement system [ 8 ]. As a result, a diagram of phases with corresponding adiabatic temperatures (in °C) was created depending on the reducers’ (Mg, C) contents (in moles) ( Figure 2 ).…”

“…Combustion synthesis (CS) fundamentally contributes to the field of green process intensification and has already demonstrated the ability to develop an extensive range of powders, near net shape products from ceramics, intermetallic, composites and multifunctional materials [ 8 ]. The intrinsic ‘green’ characteristics of CS or SHS are mainly related to the energy consumption arising exceptionally from the harnessing of heat produced during the reaction between reactants, the extremely reduced reaction time and sustainability.…”

Solid Lubrication at High-Temperatures—A Review

“…Several works have been performed in this regard to report the HT lubrication range of various metal oxides in regards to their stability, adhesion strength, and lubrication mechanism. However, in situ formation of oxides is regarded as the most efficient method due to their abrasive nature at lower temperatures [ 103 ]. Generally, under a certain condition of temperature and chemical composition, a transformation (due to changes in the crystal chemistry of oxides) from brittle-to-ductile proceeds, resulting in their easy plastic deformation.…”

Sliding Wear Performance of AlCrN Coating on TiB2/Ti Composites at High Temperatures

“…To obtain the 15-85% weight ratio of metallic and ceramic components, the precursor powders of approximately 50-50% weight ratio for Ti or Ti6Al4V and TiB 2 were mixed either by the conventional or disintegrator (DSL-175) system mixing; the specimens are designated as materials of Group I and Group II. The composites of Group III were fabricated from the powders synthesized by self-propagating high-temperature synthesis (SHS) of the elemental titanium and boron powders as detailed in [26,27]. Scanning electron microscope (SEM) (HRSEM Zeiss Merlin, ZEISS, Oberkochen, Germany) images of developed powders are shown in Figure 1 (the first row).…”