Hydrogen Embrittlement - Some interesting info
Every time someone talks about HHO for diesels, someone else brings up the subject of hydrogen embrittlement and then drops any conversation or explanation as if this will kill the HHO thread. I'm neither for or against HHO, but rather anything that will keep the Wall Street sheiks out of my wallet. So here's what my research into H2 embrittlement has found:
1. H2 embrittlement has been stated in some of the (technical) articles I found, not to be a problem in aluminum except for some very high strength alloys. In most cases, aluminum is stated not to have a problem here. So what does that tell me? Well, pistons and heads made of aluminum are not subject to H2 embrittlement so these parts of the combustion process have little worries.
2. Cast iron is next. Other articles read (by me) have stated that cast iron is not susceptible to H2 embrittlement. If fact, it is high alloy steels which suffer from H2 embrittlement. And since auto makers are not going to make blocks out of unobatanium (or any other high alloy material), the cast iron blocks should be free of any H2 embrittlement problems.
3. H2 embrittlement occurs most often in the welding of steel and steel alloys where the welding temperatures are far above combustion chamber temperatures allowing ionic hydrogen (not H2) to fuse with the steel lattice structure. Steel which have the propensity for H2 embrittlement are generally treated with heat treatments which cause the bonded hydrogen ion (not diatomic H2) to be released. And since the combustion chambers temperatures should never approach heat of fusion temperatures (unless you're running too lean and then you've got other problems), I say the H2 embrittlement argue is a moot point.
4. Now about heat treatments; what is occurring when you run your truck steady-state for 300 miles? Could you possibly be somewhat heat treating the combustion chamber and causing an outward migration of any fused hydrogen? No you say; well why was it common practice not too long ago when engine builders preferred good seasoned blocks and heads to build with? I say, the heat treating process of normal running.
5. Last point; the long carbon chain molecules of diesel fuel should in themselves contribute to H2 embrittlement. Think about it, a long molecule with plenty of hydrogens hanging around here and there, and the unburned fuel issues we have (evidenced with cat converters, acid rain and soon to come-urea injection) should cause H2 embrittlement even without the introduction of gaseous hydrogen.
So, from my perspective (and until someone actually does a study of HHO on diesels) - the nonsense of hydrogen embrittlement is just that - nonsense.
Any scientific takers?