Saxonian Institute of Surface Mechanics

The Saga of "Ultra-Hard" Nano-Composite Coatings

Marcus Fuchs' presentation (external link) which he compiled indenpendently from the SIO. His presentation does not necessarily reflect the official opinion of the SIO. SIO simply links to a presentation which fits the topic of ultra-hardness of nc-TiN/a-Si3N4/a-TiS2 coatings.

Allegations against SIO

Here you will find clarification of certain allegations SIO (or Dr. Schwarzer) are said to have mobbed Prof. Stanislav "Stan" Veprek.

Rebuttal to Stan Veprek's rebuttal

I think I can safe my energy here and simply refer to Tony Fischer-Cripps' excellent contribution, but I’d like to point out that my final conclusion was as follows:

"In my opinion and taking what I have found it is either the ultra-hardness of Veprek’s coatings or the law of energy conservation."

Otherwise I’d rather have as many people as possible reading Tony’s paper, checking upon the approaches I have suggested, using them with perhaps even increased search radius, following the paths indicated but not gone by myself, and reporting whenever there is something they think one could make better.
After all, this is not against a certain person or group, but this is supposed to be for material science and for this we do have no need for bamboozling half truths.

Feasibility of Ultra-Hardness

N. Schwarzer: "Is ultra-hardness possible - a brief feasibility study", SIO publication archive, 2012.

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Issues raised by Stan Veprek at the ICMCTF 2012

Mr. Fischer-Cripps' response (external link)

Bottom Line

In order to close this chapter of allegedly ultra-hard nanocomposite coatings which are still claimed to have ultra-hardness by Prof. Stan Veprek despite the lack of any evidence, Dr. Norbert Schwarzer has now calculated their real hardness from first principles following Mr. Marcus Fuchs' suggestion. This paper is available for free in SIO's Open Access online archive:
N. Schwarzer: „Is Ultra-Hardness Possible - A Brief Feasibility Study - Extended Edition“, SIO online archive, No. 2013-002, 2013, www.siomec.de/pubs/2013/002.

The sobering result: less than 40 GPa!

But Dr. Schwarzer's paper also presents possible theoretical solutions for ultra-hardness applying the energie approach (pp. 17-20) which, however, might be somewhat difficult to realize with earthbound materials.

Prevention of similar mistakes

In order to prevent you from accidently doing similar mistakes with regard to nanoindentation and its analysis, which may lead to strange hardness, but also elastic modulus, and yield strength results, I provide the „Ultra Hardness Checker Demo“ for free as mentioned above.

Visco-elastic material behaviour (creep) is another issue of all materials at annealed temperatures or of polymers in general, because mechanical material parameters may be time-dependent as a result. In order to test your samples for significant strain-rate dependency and, if applicable, calculate it, I make the O&PfC Creep Edition available by the end of April 2013 - also for free as its development has been partly funded by the European Metrology Research Programme Project IND05 MeProVisc which aims at improving the standard ISO 14577 with respect to nanoindentation on time-dependent materials. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.

Anthony Fischer-Cripps' responses to Stan Veprek's letter

Fischer-Cripps has meanwhile dedicated a special web page on ultra-hardness in nanocomposite coatings due to the quantity of information accumulated on this topic. Among others, it includes a list of his responses to Veprek's letter from 16 October 2012.

Stanislav Veprek's rebuttal has been rejected

The Philosophical Magazine has rejected Stan Veprek's rebuttal paper following a scientific review in January 2014. No further submissions from Prof. Veprek or his colleagues against the paper “Critical review of claims for ultra-hardness in nanocomposite coatings” by Fischer-Cripps et al. will be considered by the editor. The accepted manuscript of this paper can be found on Fischer-Cripps' website (follow the link "Author's Accepted Manuscript").
In addition, you can find the accepted manuscript of the paper “Short note on the effect of pressure induced increase of Young's modulus” by Schwarzer for educational purposes. This work covers the theoretical basics of the physical impossibility of Stan Veprek's ultra-hardness.

It seems that - at least - this time sound science has prevailed. Our thanks go to the scientists who sacrificed their precious time for this issue! And, as his entire career suddenly was in jeopardy for just asking a very reasonable question, we also thank Mr. Marcus Fuchs for his courage and unorthodox but straight thinking.

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