LaTex - Laser texturing before thermal spraying

The overall goal of the project is to demonstrate the effectiveness and benefits of laser texturing before thermal spraying in industrial environments.

The expected effects are many-fold, some of which are:

• Laser texturing gives defined surface roughness with a defined topography, can be used for a larger pool of materials and geometries, allowing broader use of thermal spraying
• Improved resource use: no need for cleaning chemicals, fresh water, grit medium and subsequent disposal, comparatively low use of electrical energy
• Better work environment: removal of noise and vibrations, reduction of dispersed particles
• Long term: implementation of compact production units to be used in a versatile manner for a resilient production

Background

Thermal spraying is a coating technique that is often used to quickly build-up thick durable coatings on various materials for surface properties, durable layers and repairs. During the coating process, a melted material is sprayed onto a roughened surface; the melt fills the cavities of the surface and solidifies in order to create a connection between materials.

The resulting adhesion is mainly mechanical; the topographic structure of the substrate surface is therefore the key to a good interlocking. Today, the necessary roughness is created by sandblasting, ie. surface bombardment with hard particles to create craters, in a multi-step process that includes pre- and post-treatments (chemical degreasing, removal of sand residues with compressed air). In this way a clean surface is achieved with sufficiently rough irregularities.

LaTex proposal

The LaTex project proposes that the current multi-step blasting process should be replaced by the single-step laser texturing process. Research has shown that laser texturing is an effective pre-treatment for thermal spraying to obtain coatings with good adhesion and long life. Highly reproducible and specific surface structures are achieved with a smart choice of laser parameters. From an environmental perspective, the implementation of laser texturing will have several positive effects: no need for chemicals, fresh water or sand; reduced electricity consumption; improved working environment by eliminating noise, vibration and dust in connection with blasting.

Project work

The goal of LaTex is to demonstrate the effectiveness of laser texturing before thermal spraying in industrial environments. To this end, the implementation of the project will be divided in four main activities:

Texture design: unlike grit blasting, laser texturing gives the possibility to obtain a defined surface roughness with a defined topography that can be optimized for each particular case (substrate, coating) but what are the guidelines to easily choose the treatment parameters?

Demonstrators of real components: once the parameters are chosen, how to go from lab scale to production line? The aim here is to manufacture real components, see the effect of the laser treatment on the component properties and how the component geometry influences the laser treatment.

The case for industrialization: what are the qualitative and quantitative benefits that are expected in terms of sustainability, production times and costs, and work environment and safety aspects? Life Cycle Assessment and business case study with regards to automation are essential in this stage.

Sharing the findings: the work in the project will cover a variety of materials, geometries and applications allowing to draw general conclusions and guidelines of interest for the thermal spray community. The findings will be shared at several levels: academic (research publications), educational (course material) and industrial (internal and external workshops).

This work will be possible thanks to the group of organizations and companies that form the project consortium, which covers the complete value chain.

The work in the project LaTex is carried out within the strategic innovation program Produktion2030, a joint initiative by Vinnova, Formas and the Swedish Energy Agency.