Abstract
The present study investigated high-aspect ratio micro-hole array parts which were made by ZrO2 micro-powder with different particle sizes and micro-powder injection molding technology. It analysed the influence of particle sizes on feedstock, debinding and sintering of ceramic nozzles with multi-micro-holes. The forming quality of ceramic nozzles with multi-micro-holes was discussed in this paper. The results show that the two mixed ZrO2 feedstocks have fine uniformity. The average deviation of the feedstock made with 200 nm powder was −2%, and the average deviation of the feedstock made with 100 nm powder was −7.1%. The sample showed certain sintering characteristics which provided better strength (11.10 MPa) to parts after debinding. The linear shrinkage and the density of the two powder samples at different sintering temperatures increased as the sintering temperature increased. If the temperature continued to increase, the linear shrinkage and the density decreased. The highest hardness and flexural strength values of the ZrO2 sample with 200 nm powder used were: 1265.5 HV and 453.4 MPa, and the crystalline particle size was 0.36 μm. The highest hardness and flexural strength values of the ZrO2 sample with 100 nm powder used were: 1425.8 HV and 503.6 MPa, and the crystalline particle size was 0.18 μm. The ceramic nozzles with multi-micro holes shrunk to nearly the same axial, radial and circumferential directions during sintering. After sintering, the roundness of ceramic micro-hole met the user requirements, and the circular hole had a high parallelism in the axial direction. The micropore diameter was 450 ± 5 μm, and it was possible to control the dimensional accuracy within 1.5% after sintering. The study presented a superior application prospect for high-aspect ratio micro hole array parts in aerospace, electronics and biomedicine.
Highlights
With the rapid development of product miniaturization, the demand for micro-bearings, micro-cams, micro-holes, micro-gears, microscope heads, micro-tubes, micro-motors and other components is increasing [1,2,3]
As the particle size decreases, the particle size of the powder decreases by 50%, and the specific surface increases one-fold, as shown in Formula (1): Sb
The optimum powder contents of various powders used in the experiment were 55 vol% using a 200 nm powder, and 50 vol% using a 100 nm powder
Summary
With the rapid development of product miniaturization, the demand for micro-bearings, micro-cams, micro-holes, micro-gears, microscope heads, micro-tubes, micro-motors and other components is increasing [1,2,3]. The finite element method has been used to simulate the rheological characteristics of feedstock and filling during the molding, debinding and sintering processes of micro-powder injection molding. This can be used to estimate the injection molding parameters, relative density, shrinkage, and relative density. Heaney et al simulated the shrinkage of debound and sintered micro-powder injection molded parts by the finite element method. To was very high, which a good guiding force and is significant for follow-up and research simulate the isothermal debinding of micro-powder injection molded cylindrical parts. The surface roughness of the sample was measured by a LEXTOLS 3000 laser scanning confocal microscope (Olympus, Tokyo, Japan), and the structure was observed with S-4700 scanning electron microscope (Hitachi, Tokyo, Japan)
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