Laser surface patterning to enhance adhesion of plasma sprayed coatings

Abstract

In thermal spraying, adhesive bond strength is a feature of surface properties. An adapted surface is studied with prior-surface treatments to enhance interface energy. This study deals with Ni-Al coatings on 2017 aluminum alloy substrate produced by atmospheric plasma spraying. The adherence was evaluated with several controlled surface topographies obtained by grit-blasting and laser surface texturing technique. Adherence has been tested with two different techniques: pull-off test and LASer Adhesion Test. They induce different stresses at the interface. The results showed that the adhesive strength is mostly controlled by a contact adhesion area. A large contact area increases the energy release rate at the interface during coating failures. The bond strength tendency for the two adherence tests is similar: apparent adherence is tripled thanks to laser surface patterning. Fracture propagation is stopped nearby laser-induced holes due to the complex shape and has to deviate inside the coating to maintain crack propagation (inter-splat cracks). The energy at the interfaces being stored locally due to pattern: pattern morphology, pattern localization and powder feed rate are important factors that control the adhesion strength of the thermally sprayed coatings.

High temperature durability of a bond-coatless plasma-sprayed thermal barrier coating system with laser textured Ni-based single crystal substrate

“…For this, a substrate surface laser patterning was used [11]. As presented previously, the patterns increased the in-contact area and provided mixedmode failures to obtain cohesive failures locally [14]. Thus, the adhesion bond strength of the thermal barrier coating was tripled with laser surface patterning prior-treatment compared to a standard preparation technique (i.e.…”

Effect of Laser Patterning Preprocessing on Fatigue Strength of Adhesive Bonded Joints Using Thin Steel Plate

“…This seems to have been caused by the improvement of the interfacial strength between the adherend and the adhesive. 15) This improvement was a result of the anchor effect, which was achieved through the fine surface roughness formed by laser patterning. This type of interfacial strength improvement through patterning is considered to have remarkably suppressed the occurrence of interfacial failure, which causes strength reduction.…”

“…Therefore, it has been applied in a wide range of fields, including the microfabrication of electronic equipment. 2023) Applying laser patterning to the adherend surface before depositing the adhesive is expected to induce the anchor effect, 15) which is caused by the increased surface roughness achieved by laser patterning; increase the adhesive area; and remove weak boundary layers, 23) such as oxides, hydrates, and deposits on metal surfaces. As a result, performing laser patterning prior to adhesion is expected to improve the fatigue properties of adhesively bonded joints.…”

Development of mathematical model of laser treatment heat processes using diffractive optical elements

“…Heat treatment is applied to improve the coating characteristics by following factors: an increase in the contact area of the coating and the substrate; reduction in material porosity; increase in the strength of interparticle bonds [7,8]. Laser treatment of sprayed coatings is one of the methods to improve coating properties [9][10][11][12].…”