Apple Patent Application Discloses Process for Creating Scratch-Resistant Stainless Steel

MacRumors · Oct 29, 2010

An Apple patent application published yesterday has been gaining some attention for its discussion of a system for creating a nitride layer on the surface of stainless steel components to assist in providing durability and scratch resistance while allowing the natural color and texture of the stainless steel to remain visible.

Cross section of nitrided stainless steel
Apple notes that the nitrided stainless steel components "can be used for a variety of applications, such as to form outer housings for a laptop computer, media players, cell phones or other similar devices." According to Apple's patent application, the stainless steel components are immersed in a high-temperature, nitrogen-based salt bath for up to an hour an half, allowing for nitrogen to penetrate the surface of the steel and combine with chromium atoms in the stainless steel alloy to create a ceramic nitride layer 15-30 microns thick on the surface of the steel.

While some reports have suggested that Apple is considering using the technology in future products, the nitrided stainless steel is likely already in use on the stainless steel band of the iPhone 4 that has garnered significant attention as part of the antenna reception issues experienced by some users. The patent application describing the technology was filed in April 2010 but is essentially identical to a provisional patent application that was filed in April 2009.

Article Link: Apple Patent Application Discloses Process for Creating Scratch-Resistant Stainless Steel

Caliber26 · Oct 29, 2010

Wait...isn't this the same metal band that people have complained so much about, in terms of scratches?

Small White Car · Oct 29, 2010

Caliber26 said:
Wait...isn't this the same metal band that people have complained so much about, in terms of scratches?

I'd believe it. I have far fewer scratches on my band than I probably should.

OllyW · Oct 29, 2010

MacRumors said:
While some reports have suggested that Apple is considering using the technology in future products, the nitrided stainless steel is likely already in use on the stainless steel band of the iPhone 4 that has garnered significant attention as part of the antenna reception issues experienced by some users.

If it is used on the iPhone 4 antenna it doesn't work very well. I've already got a couple of marks on mine where stuff has got between the bumper and the stainless steel.

jll62 · Oct 29, 2010

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The hard plastic interior of my bumper has easily scratched the band of my iPhone 4 (and no, it's not debris, it's a sharp plastic point inside the bumper). If this stuff is in use in the latest phone, it's not very scratch resistant.

Caliber26 · Oct 29, 2010

Small White Car said:
I'd believe it. I have far fewer scratches on my band than I probably should.

...and to be fair, I have zero scratches on mine (and I have no protection whatsoever on my phone), but I have seen complaints made by other posters regarding scratches. Especially those with bumpers.

sbrhwkp3 · Oct 29, 2010

My iPhone 4 has literally ZERO scratches on the band.

I didn't know how that was possible. Now I do.

jaykk · Oct 29, 2010

I have zero scratches as well(no case or bumper).

Millah · Oct 29, 2010

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I was actually going to ask of this was already on the iPhone 4s stainless steel band. Because it certainly seems like it.

People need to understand the difference between scratch "resistant" and scratch "proof". NOTHING is scratch proof. However, the i4s band seems to be incredibly scratch resistant. I've dropped my phone on a tile floor directly on the band and it only has a really tiny mark on it now. It bounced a couple times, and that's the only mark on my band. It's not even noticeable, it's just a slightly shinier spot on the band.

It's funny how people who constantly pull their phones in and out of cases get the most scratches. Kinda counter productive. That's why I never use a case, it's always better off without in my opinion. Cuz even when I dropped it I still have almost no scratches. Plus I feel like a case ruins jonys beautiful design

rprebel · Oct 29, 2010

So it doesn't stop scratches, and it inhibits reception?

*golf claps*

ipedro · Oct 29, 2010

My iPhone is naked and still no scratches. I kind of accepted that that's part of using the phone without a case but still haven't noticed anything.

CFreymarc · Oct 29, 2010

Good luck guys! Material science patents are totally out of your league.

There are tens of thousands of publicly funded material science research projects trying to mix every elemental combination to make a better material. Most innovative material science formulas never see the light of day based on cost of manufacture. There are military and aerospace materials that would make any laptop bulletproof (literally) if you are willing to spend the extra money on them.

I bet if you search German or American material science university doctorate projects, you will find something very similar to this done in the last thirty years.

iSamurai · Oct 29, 2010

I'm pretty sure this method is described in many engineering textbooks already... I thought that was an odd move because practically every mechanical engineer knows this method of surface hardening...

neutrino23 · Oct 29, 2010

This is very cool. Nitrided steel is very hard, though it falls far short of cubic boron nitride or diamond in hardness. It's interesting that they're forming the nitride from a molten salt bath. That's a real PITA, toxic too as the nitrogen comes from cyanide.

My guess is that the patent is not awarded because they discovered nitrided steel (well known for decades) but was awarded for this particular application.

Axemantitan · Oct 29, 2010

I need to get this done to my DeLorean!

Brinkman · Oct 29, 2010

I love how they go above and beyond what any other electronics manufacturer would do.

OllyW · Oct 29, 2010

iSamurai said:
I'm pretty sure this method is described in many engineering textbooks already... I thought that was an odd move because practically every mechanical engineer knows this method of surface hardening...

Nitriding has been around for years, we use TiN and TiCN coatings on our press tools at work but they alter the colour of the base metal.

unicorn025 · Oct 29, 2010

he cant get a pantent for that the steel industry all ready use that for high class stanless steel railings

Brinkman · Oct 29, 2010

unicorn025 said:
he cant get a pantent for that the steel industry all ready use that for high class stanless steel railings

Maybe there's more to the story.

JeffDM · Oct 29, 2010

Plain, uncoated stainless steel seems pretty scratch resistant. Because of the satin finish, what you do in the event of a scratch is use sandpaper with very straight, even strokes, starting with a fairly coarse grit, then successively in a few steps with increasingly finer grit.

AllGaussian · Oct 29, 2010

"ceramic nitride layer" doesn't sound very conductive or magnetic. Could this help increase the antenna performance? I didn't see anything glaring in the patent brief.

HLdan · Oct 29, 2010

I wish Apple would stop putting that stainless steel or chrome on the back of the iPod Touch. Takes less than 5 minutes out of the box to get a minor scratch on it unless it gets put inside of a case. I hate this about Apple.

AgingGeek · Oct 29, 2010

It's NOT already in use.

Has anyone taken the bumper off their iPhone to look at the frame? I have, and it's ugly. The "down" sides are all showing clear signs of rub damage. The shininess has worn off.

Maybe rub is different then "scratch"?

roland.g · Oct 29, 2010

And people are concerned as to who is going to take over for Steve.
Apple will most assuredly clone him every ten years with a decade younger and disease free duplicate. Maybe they already have.

iMule · Oct 29, 2010

Eventually, I used both my iPhone 3G and 3GS without cases and the chrome bezel had less dings than the stainless steel band on the iP4. Ridiculous how Apple's bumper has scuffed mine up so bad. I take extra care of it. It sucks for selling it next summer.

Apple Patent Application Discloses Process for Creating Scratch-Resistant Stainless Steel

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