Preparation of nano ZnO/wood composite by magnetron sputtering and its physical property change

ObjectiveIn order to improve the physical properties of wood surface, methods are explored for preparing nano ZnO/wood composite.

MethodThe 31-year-old Pinus sylvestris wood veneer was taken as the research object. Nano ZnO was deposited on the wood surface by magnetron sputtering to improve the wood function. Based on X-ray diffractometer (XRD), nanoindenter, contact angle measuring instrument and scanning electron microscope (SEM), the structure, modulus of elasticity, hardness, surface wettability and microstructure of the wood samples were investigated.

ResultXRD test results showed that when the diffraction angle 2θ was about 17.0°, 22.5° and 35.0°, there were still the characteristic peaks of three crystal faces (101, 002 and 040) of wood cellulose; the characteristic diffraction peaks of ZnO(100) and ZnO(101) appeared near the diffraction angles 31.8°and 36.3°. The relative crystallinity decreased by 23.1% when the magnetron sputtering substrate temperature was 200℃. The shape of the nanoindentation load-pressed depth curve changed greatly. The elastic modulus increased by 6.6 times, and the hardness increased by 23%. The water contact angle of the nano ZnO/wood composite surface was 140.2°. The nano ZnO of the surface had small particle size, good dispersion, flat distribution on the surface of the wood.

ConclusionThe nano ZnO deposited on the wood surface by magnetron sputtering does not affect the crystallization zone of the wood. There are still wood cellulose characteristic diffraction peaks, meaning that the crystalline structure of the wood cellulose is not damaged, but the intensity of the wood cellulose characteristic diffraction peak decreases. The ZnO film on wood veneer surface increases the elastic modulus and hardness of wood veneer surface. The surface wetting property changes from hydrophilic to hydrophobic, closes to the superhydrophobic property of ZnO. The nano ZnO film on the surface of the wood is uniform, smooth, densely arranged and without cracks. The ideal nano ZnO/wood composite with improved physical properties can be obtained by depositing nano ZnO on the wood surface using magnetron sputtering.