Authors: Jian Fang Zhou, An Li, Hong Chi Huang, Bao Lin Rao
Abstract: A polyimide-epoxy blend has been prepared by reacting epoxy resin with imide
compounds containing carboxyl groups at the ends of the molecular. When coated on the silicon steel
sheets, the blend can be used as a kind of adhesive to bind together the silicon steel sheets of
aerospace electrical machineries. Put pressure of 0.4-0.5MPa on a stack of coated silicon steel sheets,
and cured at 200°C for 2 hours, binding course of 0.01- 0.02mm on the sheets was formed. Tensile
shear strength of the binding course on stainless steal substrate is greater than 23MPa at room
temperature, 8MPa at 200°C. After enduring in air at 300°C for 48 hours the tensile shear strength at
room temperature remained 17MPa, dipping in aerospace lubricant at 250°C for 48 hours remained
18 MPa, steeping in dimathylacetamide at 160°C for 12 hours remained 12 MPa.
3055
Authors: Hong Fu Liu, Jian Long Zheng, Guo Ping Qian, Yun Yong Huang
Abstract: This paper describes the laboratory measurement of shear interface properties between asphalt pavement and concrete bridge deck using the shear test. The main factors affecting shear strength are interface frictional resistance and adhesive stress from material of waterproof layer. Firstly, we simplify the whole system by considering the asphalt pavement as an elastic layer and the cement concrete deck a rigid base. And make a sensitivity analysis on interface contact state and the material modulus of waterproof layer. The maximum shear stress increases as interface contact state changes from continuous to smooth and as modulus of waterproof layer material decreases. Secondly, an interface shear experiment is conducted with the application of portable shear apparatus. With interface shear strength as evaluation indicator, shear strength of different interface treatments is arranged in descending order, i.e. cleaning up laitance and spreading aggregate between layers; only cleaning-up laitance; leaving the surface untreated. While the descending order for shear strength of different waterproof materials can be listed as follows: SBS modified asphalt, penetration grade of 70 asphalt. Therefore, based on the laboratory test results, it is recommended that before applying waterproof adhesive layer, laitance and dust on concrete deck surface should be cleaned up and keeping it dry. And the material for waterproof adhesive layer should be SBS modified asphalt with one-size aggregate of 4.75mm-9.5 mm spreading on.
1435
Authors: Bao Wen Zhang, Jian Ping Lin, Zhi Guo Lu
Abstract: In the weld-through technique of weld-bonding process, adhesive usually suffers extremely high temperature, causing damage to adhesive and consequently the joint strength. The present work studied the effect of welding parameters on the stress distribution of weld-bonded joints under tensile loading. The adhesive properties at elevated temperatures were first presented based on the experiments. Then a finite element model was developed to predict the temperature distribution of weld-bonded joint in the welding process. Effect of welding parameters on the dimensions of weld nugget and adhesive failure zone was obtained. At last, the stress distribution of weld-bonded joint under tensile loading was studied through finite element method. It has been found that both the stress near the adhesive failure zone and the maximum stress of weld nugget decrease when the welding current increases.
128
Authors: Bin Cai, Ye Fa Tan, Long He, Hua Tan, Chun Hua Zhou, Qi Feng Jing
Abstract: In order to improve the anti-wear and anti-corrosion properties of mechanical parts used in high temperature friction conditions, the Ni-W alloy brush plating coatings were prepared and their tribological properties at elevated environment temperatures were investigated. The results show that the friction coefficients of Ni-W/GCr15 tribo-couples are in the range of 0.168～1.048, which take on the decreasing trend as the increase of environment temperatures. The wear losses of the coatings increase at elevated temperatures, and the critical temperature in which the coatings produce serious wear from slight wear is 250°C. The wear mechanism of the coatings are micro-cutting at room temperature, then it changes into adhesive wear accompanied by a certain of delamination when temperature is high than 250°C. When temperature is higher than 400°C, the main wear mechanism of the coatings is adhesive wear and delamination.
1274
Authors: Fu Xiong Wan, Wen Zhong Zheng
Abstract: To understand all-round mechanical performance of RC slabs strengthened by Carbon Fiber Sheet (CFS) bonding with the inorganic adhesive after fire, Conjugate Method is used to analyze the whole mechanical process from loading to failure. On the base of plane section assumption, Moment- Curvature curves are obtained by iterative computation program. Load-displacement curves of slabs at mid-span after fire are obtained by Conjugate Method, and furthermore, curve of moment-sheet stress relationship is obtained, stress of CFS is analyzed. The test and analysis results show that, for RC slabs strengthened by CFS bonded with an inorganic adhesive, maximum stress of composite sheet decreases with small amplitude compared with that at room temperature, and the strength of the sheet can be utilized to a great extent, even if temperature (about 200°C~300°C) an inorganic adhesive experienced outclasses softening temperatures of ordinary organic epoxy adhesives. Slabs strengthened by CFS bonded with inorganic adhesive perform good fire behavior.
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