Carbon fiber resin newbie question 1

[jamesxi]

Why are metallic resins never used as resin for carbon fibers? If I remember right carbon fiber has such a high melting point(boiling point really since it won't melt) that I would think almost any metal could be used as a resin.

 

[seneca]

Metal is indeed used as the matrix in Metal Matrix Composites (MMCs). Graphite and other fibers such as boron, alumina and silicon carbide may be used as the reinforcement. MMCs have a definite advantage over Polymer Matrix Composites (PMCs) in terms of high-temperature service, thermal conductivity and abrasion resistance, and have found applications in niche applications where high performance and light weight are worth the higher cost, primarily aerospace.

 

[Bumblebee2000]

I dont understand why people would use a Metal Matrix Composite. Why not get rid of the graphite and other fibers and make it an isotropic material? An isotropic material is easier to model and easier to predict when under loading. What advantage do you get with using the fibers?

 

[PEmrich]

Metals are reinforced for the same reasons as polymers: higher strength and stiffness, better impact properties, much higher fatigue allowables, the ability to design anisotropically.
Unlike polymers another benefit of reinforcing metals is that the density is usually reduced.
Predicting composite properties and designing with composites is much more complicated than with homogenous materials, but it is not impossible and the benefits make it well worth the effort.
Composites application growth could explode if we had a better set of rules for using anisotropic materials. Part of this is that the actual load vectors for many products are unknown, e.i. too much analysis stops with von Mises stresses.

 

[kwekch]

PEmrich make a good point on the advatage of using composites material. Bascially it is higher strength and stiffness and lower weight. However the analysis of composite material is very complicated and no two composites material are alike even if they are manufacture from the same process.
As for why carbon fiber is not use in MMC, from the cost point of view, carbon fibers are much more expensive than glass fiber. Carbon fibers cost about $12/lb where glass fiber cost around $1/lb.
From the weight point of view, i would rather use a polymer matrix composite to achieve a more significant weight reduction than a Metal matrix composites.

 

[thedude2]

As far as using a carbon fibers doesn't the thermodynamics have something to do with using this in a particular matrix?

 

[zuardy]

Hi all,
Why are metallic resins never used as resin for carbon fibers? I would answer the question with question : How melting metal (several hundred or thousand grad) can be casted to the carbon fibers?
Remember : carbon is high degree temperature act as solid fuel, right? May be some technique can be developed for that, but it must be expensive.

cheers

 

Carbon reacts with most structrual metals forming brittle intermatalic compounds at temperatures needed to enable the metal (ie cast or hot isostatic pressing) to form the composite.

 

[yvonne]

I am studying industrial design and I am now exposed to a range of plastic materials. I've been studying carbon fibers recently, and was wondering what kind of resins are used in general to formed into composite structures? Say, a piece of furniture made out of carbon fiber? And what are the general processing methods involved using carbon fiber? =) thanks people!

 

[HDS]

As allerady stated very well there are MMCs. The reason they are not common is the most common. Cost. The sample I was shown of a Boron fiber with a Titanium matrix was about the size of a sheet of paper. It cost $10,000 to make. It was made for the skin of the Nation Aerospace plane. In that application the tempertures were so high nothing else would do.
The parts were not made with a liquid resin. The material was cold formed.