Could Apple’s real watch innovation be a gold case that’s as tough as steel? 1

[MJCronin]

Is this possible ???

http://arstechnica.com/apple/2015/0...novation-a-gold-case-thats-as-tough-as-steel/

What alloy of gold could meet these claims ?????

MJCronin
Sr. Process Engineer

 

[arunmrao]

In my opinion, it is quite possible. However, it is not an alloy, but a composite material of ceramic in gold matrix. Innovative application, I agree.


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[CoryPad]

Wow, that article and its comments were gibberish. A ceramic particle reinforced gold matrix composite could reach 400 HV.

 

[IRstuff]

The way one of the patent applications reads, it's a ceramic matrix with embedded gold, according to Claim 1:

http://www.freepatentsonline.com/20140361670.pdf

However, it's still supposed to be 18K gold, which must be 75% gold.

TTFN
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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com:

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[ornerynorsk]

Typical marketing. Smoke and mirrors.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[CoryPad]

Looks like Hublot beat Apple to ceramic reinforced gold matrix composite timepieces:

http://www.hublot.com/en/collection/big-bang/big-bang-unico-magic-gold

https://www.youtube.com/watch?v=wfOV87WUL-8&feature=youtu.be

 

[CoryPad]

I don't think Apple is using a composite:

https://www.apple.com/media/us/watc.../gold/watch-gold-cc-us-20150309_r848-9dwc.mov

 

[tbuelna]

Sounds like other MMCs like those using SiC whiskers in an aluminum matrix. Would not seem hard to do given existing technology. The only hard part about producing MMCs is getting the liquid metal to adhere to the surface of the ceramic reinforcing fibers as it cools and solidifies. Aluminum/SiC MMCs require coating the ceramic fiber surfaces with a material that has a melting point above the aluminum and also allows the liquid aluminum to flow out and adhere properly.

As for the claims about surface hardness of a gold/ceramic fiber MMC, the surface would only have high hardness at locations where the ceramic whiskers are present. The surface areas between the fiber plateaus would only have the hardness of the (relatively soft) gold metal matrix.

If APPL just wanted a gold watch case with a super hard surface, why not use something like DLC over the gold? On the other hand, the gold/ceramic MMC would be incredibly strong, stiff and thermally stable. But it would also be difficult to machine, due to the presence of the very hard ceramic reinforcing fibers. You would need to machine the MMC using tools that are harder than the ceramic fibers, which means diamond or CBN.

 

[CoryPad]

Terry,

Hublot uses boron carbide reinforcement. It appears that it is in the form of a powder, with each particle roughly equiaxial and very small in diameter. Your point regarding variable hardness would be valid only at small size scales that would not be tested by regular indentation and scratch testing. I believe Hublot uses diamond tools to machine the composite parts.

DLC certainly could be an option, Apple uses it for the stainless steel version of their watch. I think one disadvantage to that would be if the coating is damaged, then the soft gold would be susceptible to damage. If a composite is used, then the entire bulk has resistance to scratches, dents, etc. For now, it appears that Apple uses a combination of alloying, casting and rolling to achieve higher strength and hardness for their gold material compared with standard 18 karat gold but not nearly the strength and hardness that a ceramic reinforcement would offer.

 

[tbuelna]

CoryPad,

Thanks for the info about Hublot's "Magic Gold". I read a bit about this material. From what I read the material starts with boron carbide powder being pressed into a mold at RT which results in a "green" preform with a low relative density. The preform is then sintered at very high pressure and temperatures which partially consolidates and fuses the particles, leaving a porous structure. This porous structure is then infused with pure molten gold at high temperature and pressure. Hublot claims the finished product meets the gold content criteria for 18k, which means the boron carbide must still be quite porous after sintering. The reinforcing fiber content of common SiC/Al MMC material is typically around 20-40%. And while the SiC reinforcing fibers used are often preforms, I don't think the distribution of the reinforcements is anywhere near as uniform as Hublot's magic gold.

 

[DeleteriousPhases]

sure is a lot of processing to obtain a final piece.

just wondering what the cost is on that.

 

[CoryPad]

The Hublot is approximately $30 000 and the Apple Watch Edition is between $10 000 and $17 000.