The main advantages of a bonding technique Compared to other linking methods of materials, bonding technology has the following main advantages:
1 The bonding material has a uniform load distribution and minimal stress concentration. Therefore, the bonded joint has a longer fatigue life than spot welding or mechanical connection.
2 For materials with different thermal expansion coefficients, flexible adhesives can be used flexibly and lowly.
3 Bonding contributes to the damping vibration of the material and improves the vibration damping performance.
4 For metal materials with a large thickness, it is not easy to bond at low temperature, high temperature or room temperature, and it is difficult to complete if a fusion welding method is used.
5 Bonding is the most perfect way to continuously connect the drop metal to the non-metal, but it cannot be bonded for the case where the two connected objects are often subjected to tear stress; or for the coated aluminum alloy, the stick should be avoided. Pickup, because in the corrosive atmosphere, the coating will be corroded, which will cause the bonding time.
Preparation of suitable surface of aluminum alloy material
When aluminum and aluminum alloys leak in the air, an oxide film can be formed immediately, and the thickness of the film layer is not uniform. This natural oxide film should be removed before bonding. Therefore, when a suitable aluminum material is prepared by surface treatment, an oxide film having a thickness of 100 to 1000 NM can be produced. The oxide film has two layers, and the underlying oxide film is firmly adhered to the surface of the aluminum material. The structure is tight, solid and corrosive, and the surface layer of the film is a porous alumina layer, which is a hexagonal rhomboid crystal. The crystal has a microporous direction and is perpendicular to the surface, and has strong adsorption properties, which is the main condition for the adhesive to bond with the aluminum surface to produce strong adhesion.
Before bonding, for example, a suitable aluminum surface can be prepared by sulfuric acid oxidation, and the temperature of the treatment liquid should be strictly controlled below 75 degrees Celsius, and the structure of the formed multi-emptive oxide film layer is similar to that of the anodized film. This oxide film layer has a strong adhesion to epoxy resin adhesive at 65 degrees Celsius, and its bonding strength is quite high. The bonded joint also has good ageing resistance.
Three binder selection When aluminum is bonded to other materials, there are many medium binders available, including various natural synthetic elastic adhesives.