Progress of wood based metal functional composites

In order to compensate for the inherent defects of wood and change the physical, mechanical, chemical and structural characteristics of wood, the research on the wood functional modification has never been interrupted. All the technologies, including the initial wood-plastic technology, impregnation technology, acetylation technology, heat treatment technology, compression and bending technology, bleaching and dyeing technology, as well as the application of microwave processing technology, have greatly promoted the development of wood science. With the deepening research on the basic physical and chemical properties of wood, new wood-based composite materials have also been applied, such as wood based metal functional composite, which endow the wood new applications, including electromagnetic shielding, heat conduction and electrical conductivity. According to the functional properties of wood based metal functional composites, which can be divided into three categories: electromagnetic shielding wood, metallized wood and impregnated magnetic wood. Electromagnetic shielding wood, mainly used for space with radiation, such as floor, slab and siding, is mainly prepared by electroless metal plating and gluing metal materials. Electroless metal plating is a chemical method for metallizing the surface of wood. Gluing metal is a method of combining metal material with wood by the help of adhesive. The electromagnetic shielding effectiveness of wood can be improved, but the damage of electromagnetic radiation to the human body reduced by all methods above. Metallized wood is a composite material formed by impregnating low-melting alloy into wood cell in a melting state, then cooling and solidifying. The melting metal uses a wood conduit as a transmission path to make the composite material compressive strength, hardness, thermal conductivity, electrical conductivity and resistance. The magnetic fluid was impregnated into the wood under a certain pressure to produce the impregnated magnetic wood, which can be used in magnetic recording, memory, electromagnetic conversion, shielding, protection, medical and biotechnology, separation and purification, and many other areas. At present, the research on wood based metal functional composites mainly focuses on the electroless plating of wood surface, but not penetrate into the interior of wood. The metal can be penetrated into the wood to form metallized wood, but the substrate used in the existing research has not been treated, the permeability of the metal is low. The focus of the next step is how to improve the substrate and then maximize the performance advantages of the metallized wood, as well as further promote the application range of wood based metal functional composite materials. In this paper, the research status of three different functional composite materials (electromagnetic shielding wood, metallized wood and impregnated magnetic wood) was summarized. Meanwhile, we also proposed the shortcomings of wood-based metal functional composites in the existing research, and looked forward to the application and development prospects of metallized wood in more fields.