|
The paper presents the effect of some surface treatment on the bonded joints strength of selected construction materials, adhesive properties of adherends after surface treatment and surface roughness. The aluminium alloys sheets, the titanium sheets and the stainless steel sheets were tested. In the experiments the following surface treatments were investigated: degreasing (chemical cleaning), mechanical treatment, mechanical treatment and degreasing, etching, anodising and chromate treatment. Adhesive joints were formed with a two component epoxy adhesive, Loctite 3430. Adhesive joint tensile-shear strength tests were performed in accordance with EN DIN 1465 standard on Zwick/Roell Z100 and Zwick/Roell Z150 testing machines. Adhesive properties were determined by surface free energy and surface free energy was determined by the Owens-Wendt method. The roughness of specimens was qualified by the method for measuring contact roughness, using an M2 profilometer manufactured by Mahr. The surface view was obtained by used NanoFocus uscan AF2. Results obtained from adhesive joint strength tests of materials evidence that surface treatment plays an important role in increasing strength of analysed joints. Tests indicate that in numerous instances this is mechanical treatment only or mechanical treatment followed by chemical cleaning which translate to the highest joint strength. The surface treatment method which introduces extensive changes in the analysed materials surface geometry is mechanical treatment. The results of surface roughness parameters measurement carried out on test samples subjected to anodising indicate that anodising has an impact on the height of surface irregularities. The application of various surface treatments in different structural materials allows modification of their adhesive properties, determined by the surface free energy. It was noted that different surface treatments contribute not only to the surface free energy changes but to the SFE components share in the total value. In the majority of variants of EN AW-2024PLT3 aluminium alloy sheet surface treatment the dispersive component amounted to the 93-99% of the total surface free energy. The assumption then should be that in order for the determination of a particular surface for adhesive processes to be comprehensive it should account for the adherends surface geometry as well as its adhesion properties. The geometry of surface can influence the mechanical adhesion and the surface free energy is connected with both mechanical adhesion and the other constituent of adhesion – proper adhesion.
|
