Decay resistance and dimensional stability improvement of wood by low melting point alloy heat treatment

Abstract

Wood has no inherent natural resistance against agents of biodegradation. We evaluated the effects of metal bath heat treatment (MBHT) on decay resistance and dimensional stability of Chinese parasol (Firmiana simplex) and Chinese fir (Cunninghamia lanceolata) wood. A low melting point alloy was used as heating medium in the treatment of the wood samples at 150, 180, and 210 °C for 2, 4, and 8 h. Heat-treated and control samples were exposed to brown rot fungus (Poria placenta) and white rot fungus (Coriolus versicolor) for decay resistance testing and anti-swelling efficiency (ASE). The improved decay resistance with increase temperatures with low mass losses of 7.3 and 7.3% for F. simplex, and 3.9 and 3.6% for C. lanceolata at 210 °C for 8 h against Coriolus versicolor and Poria placenta, respectively. ASE indicated that MBHT contributed to improved dimensional stability of both wood species after treatment. Scanning electron micrograph results indicate that metal bath-treated samples showed strong decay resistance. Therefore, our approach to thermally modify wood should be explored to overcome the energy utilization by using low melting point alloy for the heat treatment of wood.