The Saga of Ultra-Hard Nano-Composite Coatings

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Why did I prepare this presentation?

After a talk at the ICMCTF 2011 I asked a quite reasonable question, namely about certain so called "ultra-hardness" results (106 to 138 GPa) published by Stan Veprek and being mentioned in that very talk. The question simply referred to the fact of how it is possible to measure something harder than diamond with a diamond tip and thus, that one might be rather careful with such results, especially with respect to things like machine compliance, area function calibration and so on. While the presenter agreed another person in the audience apparently did not. A woman in the audience chose to grumble about my question and to ask me publicly "how I could question Mr. Veprek's results". I was ready to put the funny incident away and to go on with my daily business. But then, on the very next day, Prof. Stanislav "Stan" Veprek abused his honorary Bunshah Award lecture not only to highlight his "ultra-hardness" results again (for which he did explicitly not receive this award), but also to attack me.

The scientific community might have gotten used to critical reviewers and editors being attacked by certain authors in a most unpleasant way. I kept quiet when being called annoying critics. We might accept that grown-up scientists are taken apart publicly when only coming under suspicion of not being friends of a certain scientific finding, but when we tolerate our students being worn down only because they have asked perhaps unpleasant but still very reasonable questions, then science is dead.

That is why I chose not to blindly accept a research result I found questionable and take it as the "truth", but to stand up and question it.

Allegations by Stan Veprek in his letter from 16 October 2012

In a letter from 16 October 2012, Stanislav Veprek accuses me of having said that his "hardness measurements [...] were wrong" and claims that "his wife has not [verbally] abused" me. Those accuses are all based on Prof. Huang's statesments "I remember his question was to accuse your data", "he asked me why I referred your wrong data", "she was a little agitated" and "I don't think she was not polite" in an e-mail more than a year later and even though Mrs. Veprek's insult was partly in German.

Therefore, I asked Prof. Huang on 29 October 2012 whether or not he really sticks to what he has remembered and he answered:

(1)I accept your correction about your words of your questions were " commented that these measurements were flawed and thus these ultra-hardness results might be questionable". The use of "wrong data" was not your words, which was my interpretation of "flawed measurements", because I could not remember the exact words you used. I remember my answer to your question was that I knew the data of ultra-hardness were contraversial.

(2)The second part is on the description of the conversation between you and Mrs. Veprek. This part of description was as what I mentioned I could not remember the details, because the incident happened long time ago and English is not my native language. This part was mixed with my personal feelings and opinion. To my understanding of English, I think the conversation was within the scope of academic discussion. I don't speak German, and therefore I cannot comment your conversation in German. There were a few tenths of audiences including session chairs in the conference room. I believe every audience can have his/her own opinion.

Additionally, I would like to comment on Stanislav Veprek's statement "I only quoted Mr. Fuchs saying that 'our results were wrong' and asked him to justify his statement in the discussion after my lecture, which he did not" in his e-mail.

Since when is it considered a "fair and not unusual scientific discussion" to ask someone who is not present?

Why did Veprek quote me incorrectly as early as one day after my comment since he knew my statements first-hand from his wife?

Why did Veprek even talked about ultra-hardness in his honorary Bunshah Award lecture considering that this highly questionable part of his work was explicitly not awarded?

Stan Veprek also claims in his letter that "[he] (and with [him] the referees of [his] papers and proposals) have been accused of lies and fraud" in press releases of the Saxonian Institute of Surface Mechanics or Fischer-Cripps Laboratories.
I don't know what those press releases said, because I haven't written them. I do know, however, that I suspected this ultra-hardness myth to be a lie and perhaps a fraud in my original presentation. But I withdrew these statements at the suggestion of peers, because I was not sure of it. Meanwhile my first impression is supported by some of his former students saying they have been made aware of obtaining "the right results".

In addition, it is a crying shame that such phyiscal nonsense has passed so many peer-review processes! I would be ashamed of my Doctoral degree - luckily I don't have one.

Anthony Fischer-Cripps' responses to this letter

Tony Fischer-Cripps has meanwhile dedicated a special web page on ultra-hardness in nanocomposite coatings in order to facilitate keeping track of information accumulated on this topic. Among others, it conatins a list of his responses to Stanislav Veprek's letter from 16 October 2012.

Final Results

If you read my presentation carefully, you will notice that no proper measurements have ever been conducted independently on Veprek's ultra-hard coating samples and, hence, we will never be able to eliminate all possible effects just by analyzing the available data. Therefore, I asked Dr. Schwarzer to determine the theoretically possible hardness using first principles. He recently published his paper „Is Ultra-Hardness Possible - A Brief Feasibility Study - Extended Edition” in SIO's open access online archive. And the result is devastating:

The theoretically possible hardness
of the allegedly ultra-hard nc-TiN/a-Si3N4/a-TiS2 coatings
obtained by first principles calculations is less than 40 GPa!

As a side-product Dr. Schwarzer also evaluated parameter ranges in which certain hardnesses would in principle be possible. Finding earthbound elements and materials fitting into those parametric boundary conditions, however, might be rather difficult.

What can be done to avoid such severe mistakes?

In general:

  1. First of all, always challenge your results if there is the slightest doubt!
  2. Do not hesitate to ask very reasonable questions even if they are very basic!

With regard to contact measurements and physical surface analysis or mechanical coating characterization:

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