Conversion of biomorphic silicon carbide from wood powders carbon template

Abstract

Ecoceramic product produced by natural and renewable resources is a new variety of materials which has been widely used in industries over the recent years. A novel process regarding the fabrication of biomorphic silicon carbide ceramics has been explored from natural wood waste. The synthesis of biomorphic silicon carbide (SiC) requires two crucial processes, which are pyrolysis and silicon infiltration. In this study, the processing and characterization of silicon carbide ceramics from natural wood powders precursor was investigated by using two types of Asian wood powders, which are Kapur and Dark Red Meranti. The fine wood powders were hot pressed to obtain pre-templates, which then undergo carbonization process to form carbon templates. Pyrolysis up to 850°C was conducted in Argon flow atmosphere to produce the carbon template. The carbon template was then converted into biomorphic SiC ceramics through liquid infiltration at 1500°C. This study was to investigate the effect of infiltration holding time on the formation of dense SiC. Three different holding times of 2 to 4 hours were used during the infiltration process. Thermogravimetric analysis (TGA) was done to investigate the weight loss of wood during pyrolysis. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis were used to analyze the characteristics of the biomorphic silicon carbide. The density was determined by Archimedes method whereas Vickers hardness test was used to investigate the mechanical properties of the SiC. A homogenous microstructure was found in dense SiC consisting less than 1 µm diameter of pores. The density and hardness of the samples were found to be increase as the holding time was increased. It was found that the conversion rate of carbon into SiC was improved with the increase in holding time.