I am doing a study where I am thinking of blending zirconia and SiC powder instead of zirconia and alumina powders? Since SiC is more harder than alumina, will it give better properties?
Dear Avinash Balakrishnan ;
Zirconia alumina is basically aluminum oxide that’s been toughened up with zirconia. This makes it among the most wear-resistant abrasives, ideal for heavy grinding operations, snagging (removing sprues and parting lines on castings), and general grinding of difficult materials. whereas, silicon carbide crystals are hard, thin, and very sharp—in fact, the only materials harder than silicon carbide are diamond and cubic boron nitride. Unfortunately, silicon carbide’s hardness and shape make it brittle, so even though it cuts quickly, it also tends to break down a bit faster than other abrasives, especially under extreme forces. So silicon carbide abrasives are best suited for finishing operations such as the graining of stainless steel or where light cutting pressures are applied.
As detailed in the following references;
- https://www.mscdirect.com/betterMRO/metalworking/what-are-right-abrasives-your-metal-removal-and-finishing-work
- https://www.makeitfrom.com/material-properties/Zirconia-Toughened-Alumina-ZTA
- https://www.makeitfrom.com/material-properties/ESD-Safe-Zirconia
While studying about blend/blender ratio, it is suggested to study for more than 4-6 materials instead of two materials to get better properties.
Depending on the application, the following materials may be used namely calcium phosphate, silicon carbide, zirconia, alumina, titanium, nickel chrome, PMMA, VMMA, and some of their composites.
Dear Avinash,
at first sight this seems to be an appealing idea considering the properties of the constituents.
Your question was not very exact, do you want to blend the powders and use the loose material as abrasive (this might work) or do you intend to sinter SiC/ZrO2 ceramics for machining tools.
The latter approach is tricky as the mixture does not sinter very well, you have to apply hot pressing. otherwise the mixture is thermodynamically instable at atmospheric pressure at high temperatures and decomposes under formation of SiO2, SiO, CO, ZrSi, ZrC etc. Moreover the CTE mismatch between the two components is extremely high so that the ceramics tend to micro crack if the SiC grain size exceeds a certain limit.
Zirconia SiC composites have been described in literature with up to 30 % SiC, I never read anything on materials on the SiC rich side.
SiC due to its high elastic modulus increases the elastic constraint and impedes transformation toughening of zirconia.
best regards
Frank
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