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Proceedings Paper

Laser powder coating by multi-thin-layer technics
Author(s): Gerd Sepold; Reinhard Becker
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Paper Abstract

The laser beam is an interesting tool for production of thin surface layers. The energy input is locally limited thus leading to a snall heat loading of the substrate. The geometric dinensions of the coatings are small as compared to conventional thermal technics like surface melting and coating. In the following the multithin-layer technique is introduced. By this process coatings of small dimensions could be produced. Due to high processing speeds high cooling rates up to lO K/s are achieved by heat conduction into the substrate. This process results in fine microcrystalline structures of the deposit. Using NiCrBSi as coating material it will be shown how and to which extent different parameters influence structure and geometry of the coating. 2. MULTI-THIN-LAYER TECHNIQUE The multi-pass thin layer technique is in principle a powder feed process. Under an oblique angle a powder is blown by an inert gas stream into the laser beam. On their way to the surface the powder particles are partially heated. The surface itself is melted by the laser beam. So a good adherence is ensured between the molten surface and the impinging melting particles. This process can be repeated several times thus forming a coating by a multithinlayer technique see fig. 2. In principle the powder feed process is a well known " thick coating " process for conventional coatings like turbine blades dyes etc. /1/. In this however very small dimensions are desired which may be used for reasons of wear or corrosion resistance or for conductive or insolating layers in micro technics. In this work we investigated the influence of some processing parameters in order to achieve layers or traces of small geometries. 3. MULTIPLE THIN LAYER COATING OF NiCrBSi NiCrBSi had been used as a coating material to produce thin layers or traces. These alloys are hard and wear resistant materials which are usually applied by conventional powder spraying methods followed by arc- or flame-fusing of the sprayed layer. The main problem of conventional fusing is the high heat input of this process. Furtheron mixing of base material elements with the coating is disadvantageous. SPIE Vol. 1352 Laser Surface Microprocessing (1989) / 125

Paper Details

Date Published: 1 October 1990
PDF: 7 pages
Proc. SPIE 1352, 1st Intl School on Laser Surface Microprocessing, (1 October 1990); doi: 10.1117/12.23721
Show Author Affiliations
Gerd Sepold, BIAS (Germany)
Reinhard Becker, BIAS (Germany)


Published in SPIE Proceedings Vol. 1352:
1st Intl School on Laser Surface Microprocessing

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