Study On Enhancement Gluability Of Poplar Friction Welding

The wood friction welding technology is an attempt of traditional welding technology in the field of wood and an exploration to broaden the use of wood.However according to previous studies,the water resistance of the wood friction welding layer is not high.This study aims to improve the water resistance of the poplar friction welding layer.We conducted the following experiments: The optimum process parameters of poplar linear and rotation friction welding;The improvement of the gluing performance of poplar linear and rotation friction welding by surface treatment;The effect of gluing performance of different kinds wood friction welding by surface treatment;The effect of physical properties of poplar friction welding layer by surface treatment.The research results are as follows:(1)The optimum process parameters of poplar linear and rotation friction welding: The friction welding time of the first stage is 5s and the pressure is 0.25MPa;The friction welding time of the second stage is 18 s and the pressure is 2.5MPa;The pressure in the third stage is 3.8 MPa,and the pressure holding time is 10 s.When the ratio of the diameter of the round stick to the hole is 1.2 and the insertion rate of the round stick is 10 mm / s,the best rotation rate of the round stick is 1170r/min.(2)The dry shear strength,wood failure and wet shear strength of untreated poplar linear friction welding were 3.65 MPa,32% and 0 MPa.The dry shear strength,wood failure and wet shear strength of linear friction welding of oxidized and sulfonated materials were 5.41 MPa,63% and 1.34 MPa.Gluing performance has been significantly improved.(3)The dry tensile strength and wet tensile strength of untreated poplar rotation friction welding were 1.044 MPa and 0.363 MPa.The dry tensile strength and wet tensile strength of rotation friction welding of oxidized and sulfonated materials were3.274 MPa and 1.463 MPa.They increased by 213.6% and 303.0% respectively.Gluing performance has been significantly improved.(4)Compared with poplar linear friction welding,rotation friction welding can obtain a product with superior water resistance.(5)After oxidized and sulfonated,the dry and wet tensile strength of wood,such as poplar,sylvestris chinensis and dipterocarp,has been improved.The dry tensile strength increased by 213.6%,53.1%,and 28.4%,respectively.The wet tensile strength was increased by 303%,16.2%,and 27.9%,respectively.(6)After oxidized and sulfonated,the poplar welding layer retains a large amount of wood fiber and they are intertwined by friction and pressure.In addition,the degradation of cellulose and hemicellulose after surface modification treatment increases the relative content of lignin and increases the gluing strength of the welded parts.(7)After the surface of the poplar wood is treated by oxidation reaction,sulfonation reaction and zinc acetate,a large amount of hydrophilic-OH is consumed,so that the wet shear strength of the friction welding can be improved.(8)Untreated poplar and oxidation reaction,sulfonation reaction and zinc acetate poplar,they undergo pyrolysis reactions during friction welding,but the latter has a higher degree of pyrolysis and is accompanied by thermal oxidation.Therefore,we need to reduce the degree of carbonization of wood during friction welding.