Abstract In order to prevent the generation of a potential weakness at the substrate/adhesive interface of adhesively bonded joints, many methods were developed during the decades to pre-treat the substrates surfaces before the deposition of the adhesive. Experimental tests were carried out to simulate the real environmental conditions in which the joints have to work characterizing the mechanical properties of the joints caused by the exposition to high temperature, moisture, presence of chemical agents. The industrial need towards long-scale problem lead to the development of specific accelerated ageing methods able to induce in few weeks the same damage mechanisms within the joints which arise in years during their working life. In this work, different surface laser pre-treatments were studied with a focus on the influence that pre-treatments produce over the variation of the tensile failure load of Single Lap Joints (SLJ), previously subjected to different accelerated ageing cycles. Simple degreasing and grit blasting were also considered as reference treatments. The materials chosen for the manufacturing of the substrates were an aluminium alloy (AA 6082-T6) and a stainless steel (AISI 304). Three different accelerated ageing techniques were tested and compared to each other: (i) a cycle involving the simultaneous presence of high temperature gradient and moisture (method A), (ii) the immersion into an alkaline foam-forming cleanser (method B), and (iii) the immersion into an acid foam-forming cleanser (method C). The results showed that, while the method A did not significantly modify the mechanical strength of the joints, the method B and C resulted detrimental for the mechanical performance of the joints, even if their sensitivity to the tested pre-treatments was different. In particular, for both aluminum and stainless steel joints, it was noticed that the laser pre-treatment was able to reduce the loss of strength produced by the ageing process in comparison with the two reference pre-treatments. However, this result was also dependent of the specific value of energy density used for the laser ablation during the joints pre-treatment.

中文翻译：

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激光烧蚀表面预处理对金属粘接接头耐老化性能的影响

摘要 为了防止在粘接接头的基材/粘合剂界面上产生潜在的弱点，几十年来开发了许多方法来在粘合剂沉积之前对基材表面进行预处理。进行了实验测试以模拟接头必须在其中工作的真实环境条件，以表征由暴露于高温、潮湿和化学试剂的存在引起的接头的机械性能。对长期问题的工业需求导致了特定加速老化方法的发展，能够在几周内在关节内引起相同的损伤机制，而这些损伤机制在其工作寿命中几年就会出现。在这项工作中，研究了不同的表面激光预处理，重点是预处理对单搭接接头 (SLJ) 拉伸破坏载荷变化的影响，以前经历过不同的加速老化循环。简单的脱脂和喷砂也被认为是参考处理。选择用于制造基板的材料是铝合金 (AA 6082-T6) 和不锈钢 (AISI 304)。测试了三种不同的加速老化技术并相互比较：（i）涉及同时存在高温梯度和水分的循环（方法 A），（ii）浸入碱性泡沫形成清洁剂（方法 B）， (iii) 浸入酸性泡沫清洁剂中（方法 C）。结果表明，虽然方法 A 没有显着改变接头的机械强度，但方法 B 和 C 对接头的机械性能产生不利影响，即使它们对测试预处理的敏感性不同。特别是，对于铝和不锈钢接头，人们注意到，与两种参考预处理相比，激光预处理能够减少时效过程产生的强度损失。然而，该结果还取决于在关节预处理期间用于激光烧蚀的能量密度的具体值。对于铝和不锈钢接头，人们注意到与两种参考预处理相比，激光预处理能够减少时效过程产生的强度损失。然而，该结果还取决于在关节预处理期间用于激光烧蚀的能量密度的具体值。对于铝和不锈钢接头，人们注意到与两种参考预处理相比，激光预处理能够减少时效过程产生的强度损失。然而，该结果还取决于在关节预处理期间用于激光烧蚀的能量密度的具体值。