Example - Diamond coatings

Analysis of a DLC coating from the EU follows; return to Texas Diamond example.

			Over 100 commercial sources produce various types of DLC.
	This is an analysis of a sample from one of them deposited upon 304 stainless steel. SampleA		Notable is that even a diamond coating could not withstand the efforts of the postal and custom services, but then the layer was very thin. Immediately it suggests that a more nearly pure form of DLC could have been applied. A play of interference colors can be seen on the surface. A section was cut from the sample for analysis.
Always, the first essential to determine is the thickness of the DLC
	A bore hole can be "dug" with ions and the elements streaming back out of the hole can be identified and recorded for each depth into the coating as the hole is dug. The concentration of one element, hydrogen in this case, can be calibrated in terms of atoms/ cm³ at the different depths into the coating of DLC. Unusual in this sample is the deposition of a bonding layer of Si and Oxygen of about 1 mm thickness. The DLC coating is located by the sharp dip in Fe and Ni concentration and is seen to be 0.88 mm thick. An outer layer of fluorocarbons is seen to complete the coating package.		Secondary Ion Mass Spectroscopy (SIMS) Analysis If the sample coating were pure diamond with density of 3.5 g/ cm³ there would be 17.6 (x10²² ) carbon atoms/ cm³ . The amount of hydrogen shown by the calibrated part of the SIMS measurement would be a fraction of 3.3/17.6 or 18.8%. However, the sample is not pure diamond with a density of 3.5 g/ cm³ . While the amount of hydrogen is known absolutely the fraction that represents depends upon the actual density of the DLC.
The next concern would normally focus upon the fractional abundance of hydrogen in the DLC.
	Unfortunately, the overburdening layer of fluorocarbons "hides" the DLC layer and precludes use of the direct and cost-effective surface acoustic wave (SAW) technique for measuring the density of the DLC.		A more expensive way of measuring the H atom fraction would have to be used for this type of coating made from a package of layers. Another SIMS bore could be undertaken with the absolute calibration made upon atomic C. Motivation was insufficient to justify the increased cost of this exploratory work. However, comparison with the SIMS analysis and with the "Chart of possible fractions" for SampleB, it seems unlikely that the density would be so great as to certify the DLC of this SampleA to be significantly more pure than that of SampleB. The tentative conclusion is that this type of DLC in SampleA is good and has useful functionality, but it could be made much stronger if the amounts of diluents of hydrogen and of unconverted carbon were reduced. In that case it might even survive transit through the post and customs services.