blueandwhiteg3
Computer
- Nov 22, 2008
- 89
I'm trying to put together a ceramic metal matrix composite (prepared using hot isostatic pressing) and I'm a bit new at this, so I'd appreciate some comments. In particular, I would like input on the proposed materials' compatibility, viability, suggested ratios, suggested particle sizes for HIP, and suggested temperatures for HIP with compositions like this.
The goal is for use in a small, sheet-like part that is roughly 1 mm thick. I want extreme hardness, high stiffness and moderate impact resistance with modest weight. I want to push weight as low as possible, but also maximize desirable properties. If the properties are good enough, I could even decrease the thickness, which would be highly desirable.
I want to drive the hardness as high possible without reaching the point where it is utterly impossible to polish. The goal is to achieve extreme resistance against even minor abrasion from typical sand, etc. to the point where a polish would be easily retained over a long term. There are no special chemical exposures beyond air plus occasional sunlight and fresh water.
It would also be nice if the material could achieve a finished black-silver look when polished down. I am not very concerned about cost, even a few hundred dollars per kg for materials is not an issue. Of course, it's always nice to trim costs, but the functionality is key.
For the ceramic portion, boron carbide or silicon carbide seems like a good choice. Both achieve excellent hardness and abrasion resistance in my tests and a nice dark black glossy appearance when polished. The low density of boron carbide makes it very desirable, although I am unsure how polishable it will be, even with a boron nitride abrasives. Silicon carbide seems like a nice slightly softer alternative to boron carbide, and I know of a nearby facility that polishes and grinds it using boron nitride. Silicon carbide also has notable thermal conductivity.
I don't really see anything particularly compelling in other ceramics, they tend to be denser and less desirable in terms of color. However, I am open to suggestions, and the color issue is not a requirement.
For the metal portion, I am looking at titanium or even refractory metals. Titanium is desirable because of the excellent strength-weight ratio, stiffness, discrete fatigue limit and freedom from corrosion when exposed to air or water.
Tungsten is an appealing refractory metal due to its extreme hardness, stiffness, incredible impact resistance, and overall excellent toughness and elasticity. While I am not happy with the density, the other properties are so overwhelmingly compelling, I think it could be worth it.
Tungsten carbide might be an even better choice, being harder than tungsten and having a slightly lower melting point. Molybdenum is softer than tungsten, but also has a lower melting point and much lower density. This may make it more workable, but I am concerned that the heat required for any of these may exceed that which my HIP processor normally does. (2180° F)
I am guessing that around 60-80% ceramic and 20-40% metal would be a desirable composition. I would expect I would be pretty close to 100% density when done.
The goal is for use in a small, sheet-like part that is roughly 1 mm thick. I want extreme hardness, high stiffness and moderate impact resistance with modest weight. I want to push weight as low as possible, but also maximize desirable properties. If the properties are good enough, I could even decrease the thickness, which would be highly desirable.
I want to drive the hardness as high possible without reaching the point where it is utterly impossible to polish. The goal is to achieve extreme resistance against even minor abrasion from typical sand, etc. to the point where a polish would be easily retained over a long term. There are no special chemical exposures beyond air plus occasional sunlight and fresh water.
It would also be nice if the material could achieve a finished black-silver look when polished down. I am not very concerned about cost, even a few hundred dollars per kg for materials is not an issue. Of course, it's always nice to trim costs, but the functionality is key.
For the ceramic portion, boron carbide or silicon carbide seems like a good choice. Both achieve excellent hardness and abrasion resistance in my tests and a nice dark black glossy appearance when polished. The low density of boron carbide makes it very desirable, although I am unsure how polishable it will be, even with a boron nitride abrasives. Silicon carbide seems like a nice slightly softer alternative to boron carbide, and I know of a nearby facility that polishes and grinds it using boron nitride. Silicon carbide also has notable thermal conductivity.
I don't really see anything particularly compelling in other ceramics, they tend to be denser and less desirable in terms of color. However, I am open to suggestions, and the color issue is not a requirement.
For the metal portion, I am looking at titanium or even refractory metals. Titanium is desirable because of the excellent strength-weight ratio, stiffness, discrete fatigue limit and freedom from corrosion when exposed to air or water.
Tungsten is an appealing refractory metal due to its extreme hardness, stiffness, incredible impact resistance, and overall excellent toughness and elasticity. While I am not happy with the density, the other properties are so overwhelmingly compelling, I think it could be worth it.
Tungsten carbide might be an even better choice, being harder than tungsten and having a slightly lower melting point. Molybdenum is softer than tungsten, but also has a lower melting point and much lower density. This may make it more workable, but I am concerned that the heat required for any of these may exceed that which my HIP processor normally does. (2180° F)
I am guessing that around 60-80% ceramic and 20-40% metal would be a desirable composition. I would expect I would be pretty close to 100% density when done.
