Repeated Thermal Shock Behavior of ZrB2–SiC–Graphite Composite under Pre-Stress in Air and Ar Atmospheres

Abstract

The thermo–chemo–mechanical coupling on the thermal shock resistance of 20 vol%-ZrB2–15 vol%-SiC–graphite composite is investigated with the use of a self-developed material testing system. In each test, a specimen under prescribed constant tensile pre-stress (σ0 = 0, 10, 20 and 30 MPa) was subjected to 60 cycles of thermal shock. In each cycle, the specimen was heated from room temperature to 2000 °C within 5 s in an air atmosphere or an Ar atmosphere. The residual flexural strength of each specimen was tested, and the fracture morphology was characterized by using scanning electron microscopy (SEM). There were three different regions in the fracture surface of a specimen tested in the air, while no such difference could be observed in the fracture surfaces of the specimens that were tested in Ar. The residual flexural strength of the composite that was tested in Ar generally decreases with the increase of σ0. However, in the range of 0 ≤ σ0 ≤ 10 MPa, the residual flexural strength of the composite that was tested in the air ascended with the increase of σ0 due to the healing effect of oxidation, but it descended thereafter with a further increase of σ0, as the effect pre-stress that became prominent.

Engineered Role of SiC Particle Size on Multi‐Length‐Scale Wear Damage of Spark Plasma Sintered Zirconium Diboride

“…Among all the members from different families of ultra‐high temperature ceramics (UHTCs), including borides, carbides, and nitrides, zirconium diboride (ZrB 2 ) is a special one, [ 1 ] possessing extraordinary combination of properties, [ 2–4 ] such as high mechanical properties viz. hardness (15–29.4 GPa [ 5–8 ] ), fracture toughness (2.8–4 MPa m 1/2 [ 6,9,10 ] ), high thermal conductivity (57.9–60 W m −1 K −1 [ 11,12 ] ), low electrical resistivity (9.2–10 μΩ cm [ 13,14 ] ), and also low density (6.1 g cm −3 [ 7,15 ] ).…”

High Temperature Ceramic Materials

“…This Special Issue, “High Temperature Ceramic Materials”, released by Materials, is dedicated to original research articles from the ceramics/refractories communities, presenting some of the latest work in a few topical areas listed above. In total, 15 good quality articles have been included [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ], the interesting points from each of which are briefly highlighted as follows.…”

“…In another work [ 1 ], the promising effect of ZrC nanoparticle incorporation on the microstructure and mechanical properties of carbon fibre-reinforced SiC composites at both room and elevated temperatures has been revealed. On the other hand, by using the newly designed atmosphere-controllable “coupling thermal–mechanical material test device”, Yue et al [ 4 ] have examined the residual mechanical strength of an ultra-high temperature ZrB 2 –SiC–graphite composite under complex thermal and mechanical conditions, and evaluated its thermal shock resistance. In addition, by using a high-speed infrared camera to monitor the surface temperature of a model ceramic matrix composite subjected to different levels of uniaxial tensile stress, Kim [ 6 ] has managed to establish the relationship between the surface temperature change and the mechanical testing data.…”