Microstructure study on selective laser melting yttria stabilized zirconia ceramic with near IR fiber laser

摘要

Purpose - The purpose of this paper is to explore selective laser melting of yttria-stabilized zirconia (YSZ) ceramic by a 1 μm wavelength fibre laser; investigate the influence of different laser powers and different scanning velocities on the microstructure, the relative density, the deformation of ceramic sample and the micro-hardness; and analyze the crystal structure transformation during the fabrication. Design/methodology/approach - During the fabrication, the 5 mm × 5 mm × 5 mm YSZ ceramic samples are fabricated by rapid prototyping (RP) machine MCP Realizer SLM 250; density and microscopic photographs show the ceramic melting situation. The density of cubic sample with different laser powers and different scanning velocities is measured by Archimedes method. The microstructure of samples and powder is observed by SEM. The micro-hardness is measured by the Vickers micro-hardness equipment, and the crystal structure transition is studied by XRD. Findings - It is possible to melt YSZ powder completely with near-IR fibre laser, and the relative density of 5 mm × 5 mm × 5 mm cubic sample is 88 per cent, and the micro-hardness could reach 1,209 ± 262 HV_(500). The influence of laser power on the volume deformation is more sensitive than the scanning speed at the same energy density. The small pores and the obvious orderly cracks can be observed in the cross-section of sample; the uneven distribution of laser energy input is the main reason of the formation of orderly cracks. The transformation from monoclinic and cubic crystal to tetragonal crystal occurred during the melting process. Heat treatment (1400℃ for 30 min) cannot significantly improve the density of the sample, but it can restore the colour of ceramic. Research limitations/implications - Particularly serious due to the deformation of the ceramic material, the authors cannot prepare a large ceramic sample and measure its macroscopic mechanical properties. Originality/value - This paper describes the manufacture of YSZ ceramic sample by SLM technology with a 1 μm wavelength fibre laser, and preliminary studies show the microscopic structure, distribution of laser parameters and crystal transformation.