Abstract: The refractory diborides (HfB2 and ZrB2) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS) HfB2-ZrB2 system. Herein, a nove...

The effect of SiC content, additives, and process parameters on densification and microstructural properties of pressureless sintered ZrB2– (1–10 wt %) SiC particulate composites have been studied. The ZrB2–SiC composite powders mixed by Spex mixer with 1-2wt% C (added as graphite powder) and CMC have been cold-compacted and sintered in argon environment in the temperature range of 1800–2100ºC ...

In order to improve the high temperature oxidation and ablation resistance of C/C composites, ZrB2-ZrC-SiC ultra-high composite ceramic coatings were prepared on composites by laser cladding using Zr, B4C, Si as raw materials. The microstructure coating was characterized scanning electron microscopy (SEM) X-ray diffraction (XRD). Air isothermal (1600 °C, 80 min) oxyacetylene flame (2400 kW/m2, ...

This study examines the effects of different ZrB2 content on various mechanical properties and electrical conductivity of ZrB2/Y-TZP composite. Composites with ZrB2 content of up to 20 wt-% were particularly beneficial at the lower sintering temperature range by achieving greater densification and better hardness than Y-TZP monolith. In contrast to the trends estimated from rule of mixture, the...

The aim of this work is to optimize the oxidation resistance of ZrB2-SiC-based composites with different additives. Effect of nine factors including SiC, Cf, MoSi2, HfB2 and ZrC contents, milling time of Cf (M.t) and SPS parameters such as temperature, time and pressure on oxidation resistance in four levels was investigated. Taguchi design was applied to explore effective parameters for ...

In this work, the ablation behavior of monolith ZrB2-30 vol%SiC (Z30S) composites were studied under various oxy-acetylene flame angles. Typical oxidized microstructures (SiO2/SiC-depleted/ZrB2-SiC) observed when to Z30S was arranged vertically. However, formation outmost glassy SiO2 layer hindered tilted. The SiC-depleted region fully exposed air with reduced thickness highly Traces ablated an...

The ZrB2–MoSi2–AlN, ZrB2–SiC–AlN, and (Ti, Cr)B2–AlN ceramic composites were wetted with a nickel-based alloy in the Ni–Cr–W–Mo system. was found to wet well form contact angles θ = 0–12° for 3–7 min on their surface. wetting process less influenced by composition of main phase (ZrB2 Cr)B2) greater content SiC AlN dielectric additions, impairing composites. interaction areas studied cross-secti...

Understanding the behavior of ultra-high temperature ceramics (UHTCs) against oxidation is particular importance in high-temperature applications. In this study, ZrB2–SiC–HfB2 UHTC composites were fabricated by spark plasma sintering (SPS) method at different temperatures, times, and pressures to investigate effects process variables on their resistance. Before tests, as-sintered samples contai...