Influence of fiber coating thickness on microstructure and mechanical properties of carbon fiber-reinforced zirconium diboride based composites

Unidirectional carbon fiber-reinforced zirconium diboride based composites were fabricated by hot pressing. The fiber–matrix interface was tailored by pre-coating the as-received carbon fibers with pyrolytic carbon (PyC) coatings of various thickness or silicon carbide (SiC) coating. The effects of the interfacial characteristics on mechanical properties and microstructure of the composites were studied. The results indicated that both the composites reinforced with as-received carbon fibers and SiC coated carbon fibers showed inferior flexural strength and fracture toughness. With optimized PyC coating thickness, the mechanical properties of the composites had been remarkably improved, i.e. a flexural strength of 309.6 MPa was achieved when the thickness of PyC coating was 0.1 μm, and a fracture toughness of 6.72 MPa m1/2 was obtained when the PyC coating was 0.7 μm thick.