sinter densification
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2014 ◽  
Vol 1019 ◽  
pp. 231-240
Author(s):  
Deborah C. Blaine ◽  
Hendrik L. Bosman ◽  
Heleon H. Laubscher

Two commercially pure (CP) titanium powders, with mean particle sizes of 78 and 32 μm, respectively, were used to manufacture titanium samples via the press-and-sinter powder metallurgy process. Compaction pressures ranging from 300 to 500 MPa were used to compact the powders into cylindrical and rectangular forms. The green samples were sintered for 2 hours under high vacuum, 10-6 mbar, at 1100, 1200 and 1300 °C, respectively. Green density and green strength data were collected from the compacted samples, and sintered density, sintered strength and microstructure images were collected from the sintered samples. These data were used to characterise process models for the compressibility of the powders, and for the sinter densification, using the Master Sintering Curve (MSC) model. The results show that particle size influences the processing at both the compaction and sintering step. In modelling these two processes, separate MSC models must be characterised and each used individually to predict each one’s final sintered density. It is shown that if the densification parameter is used to characterise the sintering model, a unified Master Densification Curve (MDC) is found. The modified MDC model can be used to predict the final sintered density regardless of the initial green density or mean particle size of the powder.


2012 ◽  
Vol 710 ◽  
pp. 308-313 ◽  
Author(s):  
Suresh Telu ◽  
Vaduganathan Karthik ◽  
Rahul Mitra ◽  
Shyamal Kumar Pabi

The effect of 10 at.% Nb on the sintering and high temperature oxidation behavior of W0.5Cr0.5alloy was investigated. Elemental powder blends were made nanostructured by high energy mechanical milling, compacted and finally sintered under reduced atmosphere at 1790°C. The sintered samples were subjected to cyclic isothermal oxidation tests at 800°C to 1200°C in air. The experimental results shows superior sinterability and oxidation protection of W0.5Cr0.5alloy compared to pure W. Characterization of the oxide scales shows porous external W-rich oxide (WO3) formation which is not ideally suitable for oxidation resistance. On the other hand, W-Cr alloy with 10 at.% Nb shows the remarkable sinter densification (~98%) and oxidation resistance up to 1200°C. The oxide scale of the ternary alloy shows formation of stable Cr2O3, Nb2O5oxides and/or complex Cr-Nb oxide (CrNbO4), and there was no evidence of WO3formation in this case.


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