## 2 Materials and Methods
### Experimental Procedure
For the adhesive Scotch-Weld DP 810 based on acrylate resins the results for the tensile strength are shown in Figure 9. Values for the normal atmosphere and the argon atmosphere reach approximately similar about 35 MPa when oxidized and deoxidized. Here the strengths in the normal atmosphere also reach slightly lower values than in the argon atmosphere. The values for the argon/silane atmosphere are significantly lower, with strengths for the oxidized samples of 26 MPa and slightly higher strengths of 28 MPa for the deoxidized samples. Concerning the different atmospheres, it can be summarized that the oxygen-free argon/silane atmosphere is the only atmosphere in which no new oxide layer can form after successful deoxidation of the surface. Since determining the oxide layer thickness in the glove box has not been possible, successful removal of the oxide layer by mechanical grinding cannot be proven. However, at least the different tensile strengths for the samples ground outside and inside the argon/silane atmosphere indicate that the removal of the oxide layer was successful in the oxygen-free argon/silane atmosphere. In comparison, at least for the values in pure argon atmosphere, no differences were observed for the samples ground outside and inside the glovebox. This was to be expected, since a new oxide layer forms so quickly after deoxidation, even in argon atmosphere, that this has no effect on tensile strength. Despite all this, differences in tensile strength can already be seen in the comparison between the adhesive specimens in the normal atmosphere and the pure argon atmosphere. Since argon is an inert gas that cannot react with the adhesive, the atmosphere must have a different effect on the bond. The difference is particularly large for the epoxy-based adhesive. One possible explanation here is the reduced humidity of the inert gas atmosphere, which is 3 ppm according to the manufacturer's specification. It is known that resins, such as epoxy resins, have hydrophilic groups, which means that they attract water molecules. This accelerates the reaction, which in turn leads to a reduced degree of crosslinking, which promotes failure at lower tensile strengths. A comparison to work by other researchers on the effect of moisture on bonding also shows lower tensile strengths with increased moisture levels [3; 25; 26]. All three adhesives have in common that the values in an argon/silane atmosphere with intermediate oxide layer were below those in which the oxide layer was removed before bonding. Therefore, the bonding of pure metal surfaces has a fundamentally positive effect on the adhesive behavior of these adhesives. However, no generally valid statement can be made concerning the tensile strengths in the different ambient atmospheres since not only the environment plays a role here, but above all, the adhesive. When considering the different adhesives, it should be noted that each adhesive is based on a different bonding mechanism with a different type of bond to the surface. For epoxy adhesives, an oxygen-reduced atmosphere positively affects the strengths. A high level of cohesive failure can be seen for fracture surfaces of the adherends with tensile strengths of about 50 MPa. This indicates that the maximum tensile strength of the adhesive has been reached, and therefore no statements can be made about actual final strengths. A reduced-oxygen environment also has a positive effect on the tensile strength of polyurethane-based adhesives. It is particularly noteworthy that the deoxidized surface exhibits the highest strengths. The surrounding atmosphere also influences the tensile strengths of adhesives based on acrylates. However, it is noticeable that the argon atmosphere still provides similar values to the normal atmosphere, but the oxygen-free atmosphere leads to conjunctions with lower strengths. Since it is unclear which mechanism thoroughly explains the adhesion between metal and substrate, various theories attempt to describe this phenomenon.