| Aluminum and magnesium and its alloys are widely used in many fields such as aviation, aerospace, weapon equipment, architecture, automotive, electronic appliances and so on. Adhesive bonding joints of these alloys plays an important role in this field. Anodizing is one of the important pre-treatments to aluminum alloys for structural bonding. But the different conditions of surface treatments and drying method of anodic films of the aluminum alloys need to be investigated further. The mechanism of high-strength adhesion between aluminum alloys and rubber is less studied. The influence of the chemical conversion and anodizing of magnesium alloy on properties of the bonding joints was hardly reported.In this paper, influence of different treatments, such as sand paper, acid alkali treatment, anodizing, on the adhesive properties of aluminum alloys are studied. Also, the influence of different treatments of anodizing and drying was investigated. The results showed that the enhancement of physical and chemical reactions between adhesion surfaces which caused by the increment of the bonding surface was favorable to the bonding joint; the samples treated with abrasive papers of moderate grade sizes have higher bonding strength; the samples treated with abrasive papers before phosphoric acid anodizing had the higher peel strength and durability; the peel strength and durability of samples treated by acid and alkali had increased furthermore; after cold wind drying,50℃drying and100℃drying, the peel strength of phosphoric acid anodized samples had increased ith the drying temperature, but because of the micro cracking on the oxide surface treated by100℃drying, the durability had reduced; the drying way before boric and sulphuric acid anodizing modified by the phosphoric acid had the effect on the bonding strength, and the adhesive performance of treatment with boiling water in the closed system had a obviously decreasing; comparing with phosphoric acid anodizing, no matter what kinds of drying way, the adhesive performance of boric and sulphuric acid anodizing modified by the phosphoric acid was relatively weak.The adhesive properties between aluminum alloys with surface treatment and rubber were studied. Adhesion conditions between NBR and aluminum alloys by adjusting the ZDMA amount in the recipe of rubber or modifying metal surface by silane coupling agent was investigated. Results showed that in sulphuric acid and phosphoric acid, the thickness of oxide film would increase with anodization time increased, and adhesive properties to rubber would be strengthened; in phosphoric acid, thickness of oxide film would increase with the anodizing voltage increased, and adhesive properties to rubber would be strengthened. The bonding property of samples covered with adhesive and dried in vacuum after anodizing was better than that in atmospheric. Compared with buffing and sandblasting, peel strength of rubber and aluminum alloys treated by anodizing was the best, which failure mode was rubber cohesion failure. SEM and EDX showed that after long-time invasion and diffusion on surface of aluminum alloys, rubber molecular would continually penetrate into holes. With penetrate probability and depth growning, formed firmly physical combination with oxide film.Experiments of ZDMA showed that at first peel strength increased with the ZDMA amount increased, but peel strength began to decrease when amount was more than6phr. The most proper amount of ZDMA was about3phr. Adhesive properties of rubber and aluminum alloys surface treated by A174silane coupling agent was better than the property without coupling agent treated.Influence of chromium-free chemical conversions and anodizing on adhesive properties of magnesium alloy AZ31was studied. The results showed that the two ways both improved its adhesive strength. But the one treated by anodizing was better and got better corrosion resistance. The optimum process of chemical conversion and anodization were obtained. |
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