Synthesis, Characterization, and Microstructure of Hafnium Boride‐Based Composite Ceramics Via Preceramic Method

Abstract

The ceramic precursor for HfB 2 /HfC/SiC/C was prepared via solution-based processing of polyhafnoxanesal, linear phenolic resin, boric acid and poly[(methylsilylene)acetylene)]. The obtained precursor could be cured at 250°C and subsequently heat treated at relative lower temperature (1500°C) to form HfB 2 /HfC/SiC/C ceramic powders. The ceramic powders were characterized by element analysis, thermal gravimetric analysis, X-ray diffraction, Raman spectroscopy, and Scanning electron microscopy. The results indicated that the ceramic powders with particle size of 200~500 nm were consisted of pure phase HfB 2 , HfC, and SiC along with free carbon as fourth phase with low crystallinity.W. Fahrenholtz-contributing editor Manuscript No. 32036.

Synthesis of zirconium, hafnium and their ternary borides by a polymer complex route

“…It is noteworthy that a new peak assigned to ZrB can be observed for the XRD pattern of 1300°C, and this similar monoboride phase was also detected elsewhere [18]. After heat treatments at 1400°C, the precursor was transformed into ZrB 2 without any oxide phase, which has a visible decrease in synthesis temperature in comparison with other works [4,7,8]; however, a trace of ZrB remains in the final products. In the following heat treatments of 1500°C, the ZrB has been almost completely transformed into ZrB 2 , according to a totally non-oxidic material.…”

“…Nevertheless, these borides are expensive and are not commercially available with small particle size. Despite a large number of papers about the synthesis of metal borides [4][5][6][7][8][9], a general environmentally benign and competitive synthetic method is still looking for. In recent years, the sol-gel method is an effective method to synthesize fine boride particles and is extensively studied for its broad availability [4][5][6].…”

“…Despite a large number of papers about the synthesis of metal borides [4][5][6][7][8][9], a general environmentally benign and competitive synthetic method is still looking for. In recent years, the sol-gel method is an effective method to synthesize fine boride particles and is extensively studied for its broad availability [4][5][6]. However, the sol-gel process usually using alkoxide as metal source is extremely sensitive to moisture; besides, this process usually involves the use of hazardous solvents [4][5][6][7].…”

“…In recent years, the sol-gel method is an effective method to synthesize fine boride particles and is extensively studied for its broad availability [4][5][6]. However, the sol-gel process usually using alkoxide as metal source is extremely sensitive to moisture; besides, this process usually involves the use of hazardous solvents [4][5][6][7]. Drawing inspiration from water-soluble polymer precursor routes, which always involve the use of polyacrylic acid and polyvinyl alcohol as coordinating organic polymers to synthesize metal oxides [10,11], we come up with an aqueous polymer complex route to synthesize zirconium, hafnium and their ternary borides.…”

Synthesis of ZrC–SiC Powders by a Preceramic Solution Route

“…It is considered as a promising candidate material for rocket engines application or diffusion barrier in nuclear industry, cutting tools, and composite reinforcement . Zirconium carbide can form a protective metal‐oxide layer on material surface under extreme environments such as high temperature in oxidation atmospheres, but the generated volatile byproducts will result in the increase in porosity on the surface and the decrease in oxidation resistance of the materials . To overcome these defects, silicon carbide is generally introduced in metal carbide (MC, M = Zr, Hf) system to produce MC–SiC composite ceramics .…”