A report was performed to review the performance of some wear-resistant coatings deposited by chrome plating / electroplating, physical vapor deposition (PVD) and the Ion Beam Enhanced Deposition (IBED) procedures. The attention was to find out these coatings' usefulness for extending the working existence of precision pharmaceutical tooling. The coatings incorporated: electroplated commercial hard chrome; PVD-deposited titanium nitride (TiN) and diamond-like carbon (DLC); and IBED-deposited titanium nitride (TiN). Properties measured included covering adhesion, sturdiness and abrasive wear price. You can also read here about: Air Plasma Spray Coating and Wear Resistant Coatings
ADHESION / DURABILITY COMPARISON -
A new qualitative measurement of hardcoating durability and adhesion could be made utilizing a Rockwell "C" indent check (VDI Guideline 3198 Process). Coatings are usually deposited on a polished, hardened metal coupon (Rc> 60) to a thickness of between 1 and 3 microns. A typical Rockwell diamond indenter can be used to indent the top for a "C" level measurement (150 Kg). This steel coupon is comparable in hardness and materials kind to the precision pharmaceutical tooling that may benefit from wear-proof coatings, like punches and dies, tamping pins, and compacting rollers.
The indented area is examined at a magnification of 200X and the cracking pattern in the coating is observed. Hardcoatings with great cohesion show little if any fracture ranges extending radially from the biggest market of the indent outward towards and beyond the perimeter of the circular indent. Furthermore, no cracked islands come in the indent crater or across the crater perimeter. Hardcoatings with great adhesion display no delamination of the covering, either in the crater or next to the coating perimeter.
The outcomes of the VDI-3198 test for several four coatings tested were varied:
HARD CHROME PLATING / ELECTROPLATING -
There have been radial fracture lines following testing, indicating cohesive failure of the chrome plating / electroplating about the conical indent surface. The majority of the radial fracture ranges in the coating lengthen beyond the indent perimeter. A true number of cracked islands had been formed, but there is absolutely no delamination of the covering, either in the indent or next to it, indicating great adhesion under problems of high stress.
PVD DEPOSITED DIAMOND-Want CARBON (DLC) -
There have been many radial fracture lines and cracked islands within the conical indent zone, indicating poor cohesion overall. Most of the cracked islands had been delaminated from the top and there was total delamination of the DLC covering beyond the conical indent, indicating bad adhesion under problems of high stress.
PVD DEPOSITED TITANIUM NITRIDE (TiN) -
There was a higher density of radial fracture lines within the conical indent and past the indent perimeter, indicating poor covering cohesion and high covering friability. The current presence of cracked covering islands in the conical indent and at the indent perimeter margin, a lot of which experienced delaminated, pointed out marginal adhesion to the hardened metal substrate under problems of high stress.
IBED-DEPOSITED TITANIUM NITRIDE (TiN) -
The current presence of radial fracture lines was minimum with tearing of the coating on the conical indent surface area, indicating excellent cohesion within the coating. Some radial fracture ranges with very minor tearing of the covering were observed beyond the indent perimeter. Darkened places on the conical indent had been indicative of dirt contaminants transferred from the gemstone indenter to the indented surface area. The lack of multiple cracked covering islands indicated outstanding adhesion to the hardened metal substrate under problems of high stress.
The abrasive wear-resistant performance of coatings could be tested utilizing a Taber Abraser. Performed in accordance with standard process, SAE/AMS-2438A (SAE International), coatings are usually deposited on 3.75 inch (9.5 cm) diameter disks which are rotated against resilient rollers volumetrically impregnated with 50-micron diameter alpha-phase aluminium oxide grits. The covered disks are weighed, operate for a fixed quantity of cycles and re-weighed. The thickness of covering material worn away may then be calculated. Since standard check parameters are employed - governing grit dimension, wheel RPM and surface area loading - the wear prices obtained are directly similar as steps of how efficiently each coating would decrease the wear-price of pharmaceutical tooling.
All coatings in the analysis were deposited on 3.75 inch (9.5 cm) size, hardened (Rc 64-66) high speed metal disks which were lapped to an extremely polished finish of 0.025 micro-meter RA (1 micro-inch AA). The coatings had been deposited to comparative thicknesses, 4 microns approximately. The outcomes of the abrasive put on test for several four coatings were when compared to wear price of S7 tool metal hardened to Rockwell "C" 60.
- The wear price measured for hardened device steel (S7) was 1.3 microns per 10,000 revolutions.
- Industrial chrome plating / electroplating showed a wear price of 0.6 microns per 10,000 revolutions - or, two times less wear-price than un-coated steel.
- PVD-deposited diamond-like carbon (DLC) covering showed a wear price of 0.04 microns per 10,000 revolutions - or, 32 times much less wear-rate than un-coated metal.
- PVD and IBED deposited titanium nitride (TiN) coatings both showed wear prices of 0.015 microns per 10,000 revolutions - or, 86 times much less wear-rate than un-coated steel.