Direct metal deposition of abrasive tracks—Potentials concerning geometry and materials

Abstract

Diamond tools are essential in various industries. The high hardness of diamond enables the machining of a wide range of different materials. The materials processed with diamond cutting tools vary from ceramic or metal components to natural materials like stone. In most cases, the abrasive diamonds of such cutting tools are embedded in a metal matrix. Depending on the application, this metal matrix has to fulfill certain requirements of wear resistance in order to achieve a sufficient tool life in combination with optimal cutting results. Laser cladding offers the opportunity to produce metal bond diamond tools with different matrix materials. In this process, the matrix is applied as metal powder. Together with the diamond particles, the metal powder is blown into the focus of the laser beam. By moving the laser over the workpiece, an abrasive line trace, consisting of diamonds embedded in a metal matrix, is built. In this way, arbitrary geometries (only limited by the handling system) can be generated. For example, dot patterns or spiral tracks can easily be processed. The use of an Yb-fiber laser with high beam quality (1.05 mm mrad) enables us to build up structures with dimensions less than 1 mm. In contrast to our process, the established ways of manufacturing (electroplating or brazing) require huge efforts to produce abrasive coatings with complex shapes. In order to rate the potential of this laser cladding method, especially for small structures, 1 mm and below, the ability and the influence of different matrix materials are of great interest. Therefore, this work examines the evaluation of three different matrix materials: Co-based matrix, Fe-based matrix, and Ti-based matrix. The abrasive clads were analyzed by light optical microscopy and scanning electron microscopy (SEM); in some cases, preparation took place by focused ion beam etching. Moreover, the diamonds were chemically leached out of the metal matrix and analyzed by SEM and Raman microscopy in order to understand the interfacial reactions between the diamond and the matrix melt. The diamond strength, after the laser cladding process, was measured by mechanical tests.

A Review of the Diamond Retention Capacity of Metal Bond Matrices

“…Some instrument detection methods are used to evaluate the diamond retention ability, including SEM, X-ray diffractometry (XRD), energy dispersive spectrometry (EDS), and Raman spectroscopy [71][72][73][74][75][76][77][78][79][80]. SEM is mostly utilized to observe the diamond-matrix interfacial morphology of a fractured surface.…”

“…The reason lies in the fact that if the mixture is exposed to a sufficiently high temperature to develop a chemical bond between diamond and matrix, the diamond itself will be degraded [70]. To improve diamond retention, some new techniques have been developed, such as laser cladding [71,72] and rapid discharge sintering The addition of superfine powder or nanopowder is another effective way to improve the bonding strength [62,63]. The superfine powder can be used for reducing the sintering temperature and refining the grains which promote the performance of the matrix.…”

“…The reason lies in the fact that if the mixture is exposed to a sufficiently high temperature to develop a chemical bond between diamond and matrix, the diamond itself will be degraded [70]. To improve diamond retention, some new techniques have been developed, such as laser cladding [71,72] and rapid discharge sintering [73], in which the mixture is adequately heated to melt the matrix to develop strong chemical bonding. An advantage of these processes is a short cycle time, thereby minimizing oxidation or graphitization of the diamonds…”

Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets

“…Both materials are well described in the literature and there is extensive experimental data in their laser processing. Previous work with these materials at the University Bayreuth, Metals and Alloys include Rommel et al [ 13 ], Strößner et al [ 14 ], and Trosch et al [ 15 ], for example. The specimens for the laser cladding process are of dimensions 40 mm × 20 mm × 0.2 mm, the initial particle size of the gas-atomized powder (Dentaurum, Ispringen, Germany) is 10–30 µm in diameter.…”