The Influence of Vibro-Assisted Abrasive Processing on the Surface Roughness and Sub-Surface Microstructure of Inconel 939 Specimen Made by LPBF.

This paper presents the research results on the influence of vibration abrasive machining parameters on the surface layer integrity of elements made by LPBF technology from Inconel 939. The research was carried out on samples of various sizes on vibrating smoothing machines. The influence of the size of the processed elements, the type of abrasive shapes, the processing time, and the supporting fluid on the surface roughness and microstructure of the processed elements was analyzed. Tests have shown that as a result of using vibration processing, it is possible to reduce the surface roughness five times to the value of Ra = 1.1 µm. A significant influence of the type of abrasive shapes was found. There was no significant effect of the machining fluid on the process.

Mechanical and Thermal Properties of W-Ta-B Coatings Deposited by High-Power Impulse Magnetron Sputtering (HiPIMS).

We present the deposition and characterization of tungsten-tantalum diboride (W,Ta)B2 coatings prepared by the high-power impulse magnetron sputtering technique. We evaluated the influence of pulse duration and substrate bias on the properties of (W,Ta)B2 films. A high hardness of up to 35 GPa measured by nanoindentation was simultaneously obtained with good elastic properties. Changing the pulse duration greatly affected the B/(W+Ta) atomic ratio, which influenced the properties of the coatings. The deposited films are thermally stable at up to 1000 °C in vacuum and are able to withstand oxidation at 500 °C.

Temporal Evolution of Pressure Generated by a Nanosecond Laser Pulse Used for Assessment of Adhesive Strength of the Tungsten-Zirconium-Borides Coatings.

The article presents theoretical and experimental study of shock waves induced by a nanosecond laser pulse. Generation of surface plasma pressure by ablation of the graphite absorption layer in water medium and shock wave formation were analyzed theoretically and experimentally. The amplitude and temporal variation of the shock wave pressure was determined basing on a proposed hydrodynamic model of nanosecond laser ablation and experimentally verified with use of a polyvinylidene fluoride (PVDF) piezoelectric-film sensor. The determined pressure wave was used for examination of adhesive strength of tungsten-zirconium-boride coatings on steel substrate. The magnetron sputtered (MS) W-Zr-B coatings show good adhesion to the steel substrate. The obtained experimental results prove the correctness of the proposed model as well as the suitability of the procedure for assessment of adhesive strength.