Is dlc a rust protector though? Seem to have read many times that dlc isnt? So from a durable coating standpoint.... good........but blade corrosion protection not so. Im no expert on coatings though....maybe some expert will expand true or not routine....
From what I've come across it protects against corrosion?
Here is the link-http://www.azom.com/article.aspx?ArticleID=4125#_Corrosion_Resistance_of
Here is the text-
Corrosion Resistance of Diamond-Like Carbon Coatings
Corrosion resistance is measured by exposure for 24 hours to 10% NaCl solution at 150°F and 15% HCl at room temperature. Figure 6 (a and b) shows optical micrograph of a coated 1020CS sample after exposure to HCl and brine solutions showing that DLC-Si coating provide excellent corrosion protection for the substrate. It is because DLC is chemically inert and acts as a physical barrier between the substrate and corrosion environment provided coating defects are minimized. It can also be noted that there is no corrosive undercut from the Rockwell C indent that was intentionally done to breach the coating, or from the exposed edges of the saw cut section, indicating the good adhesion and chemical inertness of the coating layer, at the interface with the substrate, as suggested by the TEM images.
Sour Autoclave Corrosion Test for Diamond-Like Carbon Coatings
Another corrosion test which the coating has been subjected to is a sour autoclave per NACE TM0185 standard. This is a three phase test (aqueous phase distilled water, oraganic phase xylene, gas phase 1% H2S, 85% CO2, 14% methane) which is done at high pressure. Figure 7 shows the film (entry, middle & exit film of the pipe) before and after this aggressive test. It can be noted that the coating passed the NACE standard test with no damage or blistering of the coating occurring and additionally passed the standard 67V pinhole test before and after autoclave exposure. This test is well known within the oil and gas industry as a good measure of how corrosion resistant the coating is.
Conclusions
A novel hollow cathode plasma immersion ion processing method is developed and used to deposit silicon containing diamond like carbon (DLC-Si) films inside a one foot long 1020CS pipe with 1.75 inch diameter. A layered coating structure was developed, including an improved adhesion layer with good mixing of substrate and coating constituents, to improve adhesion of the coating while a DLC top layer provided excellent wear and friction characteristics. Data showed that such a coating provides excellent corrosion protection to internal surfaces of pipes. Application of this coating technology is in industries such as oil and gas, tribological and corrosion performance improvement is expected for components such as pump barrels, downhole pipes, drilling fixtures, and drilling bores, etc.
A complete set of references is available be referring to the source document.
Authors: B. Boardman, K. Boinapally, T. Casserly, M. Gupta, C. Dornfest, D. Upadhyaya, Y. Cao and
M. Oppus
Source: Corrosion and Mechanical Properties of Diamond-Like Carbon Films Deposited Inside Carbon Steel Pipes by Sub-One Technology
Here is the link to what Michael Janich had to say over on Spyderco's forum-https://www.spyderco.com/forumII/viewtopic.php?t=61572
Here's the text-
DLC (Diamond-Like Carbon) is molecularly bonded to the surface of the material and will not "chip off if hit hard enough." It also does in fact increase corrosion resistance.
For a more technical explanation of the process used to apply it and the benefits of the coating itself, I went to IonBond, the folks who developed it. This is from their web site:
PACVD Technology
PACVD (Plasma Assisted Chemical Vapor Deposition) is a vacuum based process used to deposit DLC (Diamond Like Carbon) coatings, also known as ADLC (Amorphous Diamond-Like Carbon). All educts of the PACVD process are gaseous. This makes it suitable for coating 3D components uniformly, without the need for rotation as is necessary in PVD.
The coatings are amorphous in structure and contain around 70% sp3 bondings, which accounts for the high hardness of the coating (10-40 GPa).
The PACVD process is used for coating a very broad range of conductive and non-conductive substrate materials at temperatures below 200° C. The typical thickness is in the range of 2 3 µm.
DLC coatings feature excellent hardness, wear and low friction properties under dry or deficient lubrication conditions. They are ideally suited for tribological systems found in engines, machines and other mechanical assemblies with sliding and rolling movements. The perfect surface finish without any post-treatment makes them ideal for high precision injection molding tools as well as for decorative purposes. DLC is chemically inert and biocompatible which allows for its application on medical components and implants.
Broad range of substrate materials
No distortion of high precision substrates
No post treatment necessary
Gaseous process for uniform coating of 3D geometries without rotation
Green technology with respect to educts, process and products
Here's a link to additional information that substantiates its qualities of hardness, adherence, and corrosion resistance:
http://www.renishaw.com/advancedmaterials/en/diamond-like-carbon-coatings--14211
In my previous job, many of the knives we produced were DLC coated--including DLC-coated A2 tool-steel blades. I saw many of these that had seen extensive hard use in tactical environments. The DLC held up extremely well. Even when the exposed steel at the edges of blades was allowed to corrode, the corrosion did not "bubble" under the DLC like conventional coating or plating processes and stopped where the DLC started.
I hope this helps.
Stay safe,
Mike
