H. Myalska

Microstructure of in situ Mg metal matrix composites based on silica nanoparticles

Metal matrix composites comprising a magnesium matrix and Mg2Si/MgO dispersoids obtained by hot pressing silica nanoparticle agglomerates and metal powder in a Degussa press were characterized. Two powder mixtures having weight proportions of Mg:SiO2 of 10:0.3 and 10:1 were identically sintered. Their microstructures were characterized by optical microscopy and X-ray diffraction. The size and distribution of the Mg2Si and MgO dispersoids formed in situ were assessed as a function of the original nanosilica content. The behaviour of the composites under compression testing was assessed in 3D by X-ray microtomography using 225kV Nikon X-tek and 150kV Xradia MicroXCT scanners. This provided insights into composite strengthening mechanisms and matrix particle decohesion.

Microstructure Characterization of Superfine WC-Co Powders

In this paper results of tests concerning the WC/Co fine-crystalline composite powders type 88/12 and 83/17 provided for thermal spraying of layers resistant to abrasion are presented. Tests which characterize basic technological properties were performed since these properties are essential from thermal spraying point of view. Microstructural properties are essential as well because they allow evaluation of morphology of powders by SEM method with an analysis of chemical composition in micro-areas. Moreover, the phase composition was characterized by XRD in macro scale and by EBSD in microareas including distribution maps of individual phase components in all particles of the powders.

Microstructure and Selected Properties of WC-Co-Cr Coatings Deposited by High Velocity Thermal Spray Processes

Selected information about high velocity thermal spraying method were presented in this article. Three generations of thermal spraying processes based on oxygen with propane mixture, liquid fuel with oxygen and propane with air were characterized. A powder of WC-Co-Cr 86-10-4 was used for coatings deposition on a steel substrate. Four coatings were deposited by different thermal spraying systems such as Diamond Jet, JP 5000, Micro HVOF and HVAF.

The Influence of High Velocity Thermal Spraying Methods on Top Surface Topography of WC-Co Coatings

Characterization of top surfaces of WC-Co coatings obtained during deposition process of high velocity thermal spraying type was showed in this article. The feedstock powder was so called “superfine” powder of WC-17Co types produced by Inframat. In first part of article short characterization of powder was presented, especially characterization of it morphology including shape, internal microstructure and grain size description. The second part of article is dedicated to characterization of microstructure and topography of top surface of coatings deposited by two different methods of high velocity thermal spraying. In this case analysis of top-surface condition by scanning microscopy with chemical analysis in microareas was used and as well as a qualitative and quantitative analysis of topography of carbides surface by traditional non-contact and laser profilometry.