Hey guys, I was looking into machining a mini housing and rotor for fun. Of course, I went straight down the rabbit hole on re-engineering housings, and found some potential innovations. Any feedback or results from people who've already tried these would be much appreciated! Also happy to hear other cool ways to potentially bump up performance, but here's what I'll start with:

TiCN coatings:
I haven't seen or heard of a TiCN coating used on engine internals before. But based on some quick research, I think this has huge potential, especially for billet parts. This is basically a super thin film of TiN and TiC particles which can bond to most metals, especially aluminum.

Pros:
- Creates a low friction surface (lower than hardened chrome)
- Ridiculously high surface hardness rating (3X hardened chrome, harder than carbide)!
- No tolerance changes required due to coating thickness (~3um thick)
- Should be easily able to withstand the heat of a rotary engine
- Offers significant wear resistance, especially abrasive wear

Cons
- No idea how big of a deal it is to apply this coating
- Not much support in automotive applications from what I've seen, yet

I think this could be a real game changer if we find a way to test it. I can't see why this wouldn't work yet! Here's some sources:
https://www.brycoat.com/surface-engi...ticn-coatings/
https://www.sciencedirect.com/scienc...77705813020985

Ceramic heat dispersion paint:
Another coating, this time for the external surfaces of the engine. There are plenty of ceramic powder coat paints available now that increase the thermal conductivity of the applied surface. This helps the parts dissipate heat better without any mechanical alterations. Hard to say no to better cooling.

Pros:
- Affordable
- Easily applied via powder coating
- Again, excellent heat resistance and heat dissipation
- Preserves externals if you care for aesthetics

Cons:
-???

No idea why we wouldn't use this either. Here's some more links:
https://images.nicindustries.com/cer...088.1599852278
https://www.hmelliottcoatings.com/th...rsion-coatings

So with that all said, try and shoot these ideas down! Maybe we're on to something, maybe not. Either way, let's hear about some innovative ways to bump performance.

 

If it's very hard, I'd be concerned about it flaking off. The rotor housing flexes and warps all over the place with all the different stresses and loads. That's why Mazda chromes a corrugated steel hoop, not direct to aluminum.

 

I’m pretty sure the TiCN forms a molecular bond via a chemical reaction with the material it’s applied to which is apparently known for being extremely strong. I think the only way it would flake off would be from excessive temperatures in the combustion chamber. Your point with the steel is interesting because in machining, tools coated in TiCN are usually HSS (high speed steel), so maybe we can figure out how it deals with thermal deformation based on how TiCN tools might perform when overheating.

 

I'm thinking of the immediate stresses as the apex seal rides over it. There's some pretty significant pressure loads, even before the seal starts bouncing. Mazda battled this for years with the chrome, and kept making the seals lighter and lighter to reduce loadings.

 

the early race housings (up into the late 80's for sure) were chrome plated right on the aluminum, the plating does fail, it does this thing that looks like scales of a fish.

incidentally i read a book about the Porsche air cooled engines and the piston sleeves go through a similar evolution as the rotor housings. the VW bug starts with iron cylinders and they eventually have to go aluminum, and they try a few coating before they find one that doesn't suck/fall off.