Electroless nickel-boron coating on B^sub 4^C-Nano TiB^sub 2^ composite powders

• Published in: International journal of refractory metals & hard materials 2018-11, Vol.76, p.58
• Main Authors: Heydari, Mina Saeedi, Baharvandi, Hamid Reza, Allahkaram, Saeed Reza
• Format: Article
• Language: English
• Subjects: Boron; Boron carbide; Coating effects; Composite materials; Electrodes; Electroless coating; Electroless nickel plating; Morphology; Nanocomposites; Nickel; Plating; Plating baths; Powder metallurgy; Sinterability; Sol-gel processes; Synthesis; Titanium diboride; X-ray diffraction
• ISSN: 0263-4368

B4C-TiB2 nanocomposites have high hardness of boron carbide and high strength and toughness of titanium diboride. One of the most important problems in adding TiB2 powder to B4C powder is its lack of uniform distribution in the final powder, so in this research we have tried to synthesis B4C-Nano TiB2 composite powder by sol gel method. Also, since coating by electroless method has been introduced as an effective way to improve the homogeneity and sinterability of ceramic composites containing a small amount of metal phase, the surface of B4C-Nano TiB2 composite powder is coated by electroless nickel-boron plating and the effect of C2H8N2 complexing agent at temperatures of 75, 85and 95 °C and pH 13 is examined. Scanning electron microscope equipped with EDS analyzer for investigation of microstructure and morphology of coated B4C powder and X-ray diffraction to determine the composition and phases were used. The results indicate that the calcination temperature of 1200 °C and 60 min duration is quite appropriate for the synthesis of B4C-Nano TiB2 composite powder. It was also found that in the electroless coating process, the amount of the C2H8N2 complexing agent in the plating bath has significant effect on the quantity of coating and uniformity of it on the surface of the B4C particles. By increasing the amount of C2H8N2 in the electroless plating bath in each of the temperatures 75, 85 and 95 °C, the nickel-boron coating is reduced. The highest amount of nickel-boron coating was achieved on the surface of B4C-Nano TiB2 composite powder at 95 °C and the nickel salt to complexing agent ratio of 1: 6 (20.55 g/l).