Titanium diboride (TiB2) is among the family of transition metal compounds that are regarded as ultrahigh temperature ceramics [1]. TiB2 ceramic matrix possesses some excellent properties such as chemical stability in harsh environments, high melting points, good thermal conductivity, good abrasion resistance high strength, and hardness [2–4]. These properties have made it possible for TiB2 to be used in various applications viz aluminium evaporator boats, cutting tools, ballistic armour, wear-resistant parts, etc [5, 6]. Despite the excellent performance of these materials in service, their poor self-diffusion coefficient, high melting point, the existence of oxide contaminants (B2O3 and TiO2) on the powder surface of TiB2 and strong covalent bonding pose some challenges in densification of monolithic TiB2 [6, 7]. Previous works have stated that in achieving a theoretical density of more than 98% of a monolithic TiB2, an elevated consolidation temperature with high external pressure is required. However, grain growth developed at these high consolidation temperatures often reduces the flexural strength and fracture toughness as well as some of its intrinsic properties [8, 9]. Thus, numerous works have been done to enhance the mechanical properties and the sinterability of TiB2 ceramics materials via the introduction of non-metallic additives and metallic as sintering aids. Metallic additives such as Fe, Al, Ti, Cr, Ta etc, are applied for TiB2 ceramic densification but their usage has been limited as a result of their depreciating effects on the high-temperature application of TiB2. Owning to these challenges, attention has been shifted to densifying TiB2 with the use of non-metallic additives which are mostly carbides, silicides, nitrides and borides-based sintering aid such as, AlN, TiC, WC, Si3N4, NbC, SiC, ZrB2 [10–14]. These additives remove oxide layers from the powder surface or create in-situ phases which contribute to the composites’ sinterability and properties enhancement [11, 15, 16].
Spark plasma sintering is the one of the fabrication processes that is used for the consolidation of TiB2 ceramic materials. This technique uses a lower temperature to achieve the densification of ceramics material under low pressure at a short dwell time, these have made SPS gain high predominance over other conventional sintering viz, hot press, hot isostatic press, etc. The application of SPS ensures the achievement of high densification, finer microstructure and excellent mechanical properties [17–19].
In addition, the importance of fine microstructure, peak densification and excellent mechanical properties cannot be jettisoned in the enhancement of wear performance. Hence in the achievement of these features, judicious selection of the type of sintering additives/matrix and their right composition has a lot of priority. The utilization of ceramic matrix composites for cutting tools and other applications where wear behavior is highly considered, certain things must be measured so as to design the type of materials that can withstand the wear rate, thus the type of load, time and the type of medium the material will be used will be put into consideration. It has been studied that under dry sliding parameters that the tribological performance of ceramic components is difficult and reliant on some outward conditions such as sliding speed, humidity, temperature, load counterpart atmosphere, etc [20].
Past works have emphasized the influence of carbides and nitrides reinforcement on the relative density and mechanical features of borides ceramic. The inclusion of 5 wt% silicon nitride (Si3N4) in TiB2 ceramic matrix as a sintering aid was observed. It was reported that there was a densification increment when it was sintered via SPS at the temperature of 1900°C under 40 MPa for 7 min. [4]. It was reported that the incorporation of 2.5 wt% Si3N4 to TiB2 matrix enhances the sinterability of the composites significantly when it was hot-pressed at 1800°C for 1 h [6]. The examination of the impact of diverse composition of SiC particulates under varying sintering parameters were studied on the consolidation of TiB2 based composites. A densification of 99.5% was attained at the temperature of 1800 ℃ under 30 MPa for 15 min. Although, at 1600–1800 ℃, under 10–30 MPa for 5–15 min the composites were consolidated [7]. At the grain interface of the reinforcement (SiC) and the matrix (TiB2), the secondary interfacial phase (TiC) which was created via the reaction between the surface oxide contaminants and the SiC particles was reported to improve the densification [10, 21, 22].. An examination was carried-out on the influence of TiN and SiC as an additive and reinforcement on TiB2 based composites synthesized via SPS at 1900°C for 7 min under 40 MPa. A densification of 99.9 % was achieved for the composites of TiB2–SiC (20 vol%)-TiN (5 wt%) and TiB2-SiC (20 vol%) [23] in contrast to the undoped TiB2 under similar sintering parameter which has its densification equal to 96.7% [4].
The inclusion of TiN and SiC was reported to form an in-situ phases, which concurrently improve the densification and sinterability of the two samples [4, 24, 25]. Finer microstructure was examined to be produced because of the addition of TiN, this experimental work also concur with Shayesteh et al [26], when he only used TiN as a dopant for TiB2. Alexander et al. [27] studied the wear performance of B4C-carbon nanotube and achieved a specific wear rate of 1.06 X 10− 6 mm3/N.m which was less than the undoped B4C ceramics. Murthy et al. examined that the addition of ZrO2 to B4C ceramic matrix, created in-situ ZrB2 and consequently round pores of sub-micron size were similarly formed. Hence, the establishment of CO gas could aid to arrest and/or deflect cracks, thus enhancing the tribological behavior of B4C ceramics. Sharma et al. [28] stated that with a rise in load, the specific wear rate of SiC decline and then the coefficient of friction initially increase and then decline. Sonber et al [29] discovered that the specific wear rate of B4C enhances with a rise in load, consequently, its coefficient of friction declined.
Profound works have been carried out on the microstructure, densification and mechanical properties of TiB2 using SiC as a sintering additive, but little or no work has been reported on the influence of microstructures and mechanical properties of this composite on it wear performance. Therefore, in this study, the impacts of SiC on the microstructure, relative density, and mechanical properties and the wear performance of TiB2 ceramic were observed, and more importantly, the influence of these aforementioned properties was study on the wear behavior of TiB2-SiC.