木材表层热处理的研究现状与发展趋势

Surface Heat Treatment of Wood:Present Situation and Development Trend

常规热处理在改善木材尺寸稳定性的同时会削弱其力学性能,因此亟需开发能够有效平衡木材尺寸稳定性与力学性能的新型热处理方法。木材表层热处理不仅保留了热处理作为环境友好型改性方法的优势,同时兼具改善木材—水分关系以及维持力学性能的特点。文中阐述了表层热处理木材的形成要求,即处理时需在木材表层产生不少于3%的质量损失,且芯层无明显质量损失;总结木材组织结构和处理工艺对表层热处理木材性质的影响,归纳目前表层热处理的技术方法;指出热板法和介质传热差法是现阶段表层热处理的主要方法,木材初含水率是影响热板法处理效果的重要因素,介质传热差法在处理深度和处理设备等方面较热板法具有优势和应用潜力;最后,对木材表层热处理技术的进一步开发与应用提出了建议。

Conventional heat treatment increases the dimensional stability of wood while decreasing its mechanical properties.Therefore,it is critically needed to develop innovative heat treatment methods that can efficiently balance the dimensional stability and mechanical properties of wood.In addition to maintaining the advantages of heat treatment as an eco-friendly modification method,surface heat treatment of wood can improve the relationship between wood and moisture and keep the mechanical properties of wood.This paper reviews the requirements for the formation of surface heat-treated wood,which include no less than 3%of mass loss on the surface layer of wood and little or no mass loss in the core layer during the treatment.The effects of wood structure and treatment processes on the properties of surface heat-treated wood are summarized,along with the current methods used for surface heat treatment.Currently,the hot plate method and the medium heat transfer hysteresis method are the primary techniques used for surface heat treatment of wood.The initial moisture content of wood is an important factor influencing the effectiveness of the hot plate method,while the medium heat transfer hysteresis method has advantages and potential application in terms of treatment depth and equipment.At the end,suggestions are put forth for further development and application of surface heat treatment of wood.