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History of CRODON®
Hard Coat wear plate and tile

HISTORY    APPLICATIONS    TESTING

 

The Idea:
In early 1998, Chromium Corporation became aware of a problem in coal-fired power plants that we thought we could address. Wet, fine-grained coal was sticking to the sides of chutes leading to the crushers, storage bids/silos, and burners. Many of these areas also experienced severe wear and impact. We knew that CRODON wear plate in general was an excellent surface for environments requiring low friction, easy release, and non-stick characteristics. We also knew that CRODON wear plate presented one of the hardest, most wear resistant, and adherent, surfaces in the industry.

Additional investigation revealed that similar conditions existed in a wide array of industries. End users usually tried to solve their problems by lining surfaces with high-density plastics, high alumina ceramic tiles, special alloy wear plates or chromium and tungsten carbide hardfacing. Plastics wore out quickly when exposed to dry abrasive materials; ceramics didn't stand up to impact; alloy wear plates allowed material to stick and build up on their surfaces; and carbide hardfacing was expensive, required thick applications for long life, had poor release qualities and didn't stand up to impact. Our challenge was to determine whether our CRODON wear plate would perform well under all conditions. Long duration field-testing and bench testing has shown that it does.

The Product:
CRODON wear plate is a proprietary process that applies a dense, highly adherent layer of abrasive and impact resistant material to the surface of ferrous-based materials. The final product can be produced in flat "wear plates" and "strips". It can also be fabricated to unique dimensions or rolled on the I. D. or O. D. to dimensions as tight as 5" on the radius.

Standard thickness of the CRODON wear surface is 0.020" though thicker plates up to 0.100" are available as special order. We produce four varieties of CRODON wear plate depending on the application environment.

• Standard CRODON wear plate uses mild steel up to ½" thick as the backing material. This product group is for environments needing resistance to impact, abrasion and sticking but where mild steel will stand up to the environment long enough to allow replacement on a scheduled basis once the CRODON wear plate has been worn through.
• CRODON Plus wear plate uses a proprietary 400 Brinnel through hardened steel as the backing material. This product group is for environments with severe impact or where mild steel would not provide sufficient lead time to perform maintenance replacement on a scheduled basis.
• CRODON Premier wear plate uses a proprietary 500 Brinnel through hardened steel as the backing material. This product group is for environments with severe abrasion where mild steel and 400 Brinnel steels would not provide sufficient lead time to perform maintenance replacement on a scheduled basis. This product group is NOT recommended for impact environments.
• CRODON Stainless uses stainless steel as its backing. This product group is targeted for high corrosive environments where the back side, edges, or fine cracks (from rolling/bending on the outer diameter) would be subject to corrosion.
• Edge Protected CRODON wear plate is a special service where we can apply the CRODON wear surface to edges of the base material. This is important because any unprotected area that is subjected to wear or impact becomes the weak point in the material. In installation edges must be mated flush or edges must be protected to prevent wear from beginning at the edge and wear under the protective CRODON wear surface.

The Markets:
Markets are diverse and geographically dispersed. At a minimum, available markets include coal fired electric generating plants, sand and cement manufacturers, pulp and paper mills, wood and lumber mills, material handling silos, barges and rail cars, foundries, mines, and roofing shingle manufacturers. Any operation with problems involving sliding wear, abrasion, erosion, impact, and sliding/sticking concerns is a candidate.

Field Testing:
We have conducted field tests to evaluate the performance of CRODON wear plate in all performance areas: abrasive wear, impact, and sticking. Three initial trails were conducted in electric power plants fired with lignite coal and one test was in a manufacturing facility producing asphalt-roofing shingles with abrasive granite-chip surfaces.

1. The shingle plant test compared ¼" ceramic tile to our "tile" with .020" of chrome in an extreme wear environment. In this particular location, plant personnel reported a life cycle of two to four months for the ceramic tile. Additional problems were caused when ceramic tile broke during production line adjustments or the epoxy adhesive failed due to continual vibration and impact from production activity. Detailed tracking of the "test" pieces was stopped after 9 months of service, though the CRODON wear tile was still not worn out. In other locations, star wheels, high lug, "T" bars, fife paddles, and granule chutes have show similar or better results compared to ceramic, AR, and chrome carbide weld overlay. An additional benefit that has been identified is elimination of cleaning of operating surfaces. Nothing sticks to the CRODON wear surface. This saves time, improves productivity, and eliminates a potential safety hazard.
   
   
2. In the first power plant we replaced an alloy wear plate acting as a "bang board" for lignite coal prior to entering the crusher. Besides large coal, the material stream included petrified wood, rocks, and other hard materials. Prior to installation the maintenance manager reported a standard life cycle of 6 to 9 months for alloy wear plates when under normal use.
   
   We used a standard ½" thick piece of mild carbon steel with .020"of CRODON wear surface. After more than six months, there was no measurable wear to the board and only limited chipping along top edge. The CRODON wear plate lasted just over 20 months before needing to be replaced. The mode of ultimate failure was a cohesive failure of the base material which eventually caused a section of the material to come loose in the middle of the plate. The maintenance manager commented, "We've never seen anything like it." Since then, they have converted all their impact applications to our second generation solution for impact, CRODON Plus wear plate. To date, we've not seen any failures and expect a life cycle 2 to 3 times that of the standard CRODON wear plate in these applications.
   
   
3. The third test compared standard alloy wear plate with a .020" thick CRODON wear surface on ½" of the facility's standard AR plate against sliding lignite coal in a delivery chute. Maintenance managers reported an average life cycle of 6 months in this location before significant repairs would be needed. The application tested resistance to extreme wear, limited impact, and severe sticking. During inspections, coal was regularly seen adhering to the standard alloy wear plates in the chute but our piece remained clean. There was no noticeable consequence due to impact. Wear patterns on the other areas of the chute were extreme showing worn pathways over ¼" deep. The CRODON wear plate was in service from early 1999 through 2002. This location has become a major user of our wear plate for all severe service chute locations in the facility.
   
   
4. Our final test began in the summer of 1999 and evaluated the ability of CRODON wear plate to resist extreme sticking and erosion related wear. A CRODON wear surface 0.020" thick was clad on mild steel and installed on a gate that diverted limestone slurry into holding bins. Standard materials were alloy wear plate that lasted up to two years - when worn areas were repaired with weld-on patches. The limestone slurry would stick and build up on the alloy steel materials until it became a "cement like" mass that would block the diverter gate. Plant maintenance personnel would have to climb the tower and wash down or shovel off the buildup several times a day.
   
   Since the CRODON wear plate was installed, the diverter gate has never needed cleaning and is still in service with no measurable wear.
   
   
5. Since these initial field trials, additional installations have been made in sand and gravel quarries and processing facilities, asphalt plants, mining operations, port terminals, conveyor systems, coal stacker/reclaimers, and cement facilities. To date we've seen outstanding results in all these applications solving problems and extending life cycle with a product that's easier to install and often weighs only half as much as competitive materials.

Lab Testing:

1. We performed the "Slurry Abrasion Resistance" (SAR) tests comparing CRODON wear plate with a competitive ceramic material. The SAR is a reciprocating wear test in a controlled slurry abrasive. The results indicated that the CRODON wear surface had 10 to 15 times better wear characteristics than the competitive ceramic material.
   
   
2. Utilizing the ASTM G65 method, modified with coal slag as the abrasive, showed that the CRODON wear surface at 0.020" thick had a life cycle equal to 0.317" of ceramic on a strict wear basis. Note that most ceramic fails long before the full thickness is worn through and that CRODON wear plate lasts through to initial wear surface to the base material which can be high carbon, through hardened AR plate. Extended to the best through hardened AR plate, the CRODON wear surface at 0.020" thick had a life cycle of up to 3" of high carbide, through hardened AR plate.
   
   
3. Impact testing has conducted for ballistic and simple impact (ball drop) applications. Ballistics testing with a 30 caliber round showed that CRODON wear plate with a 0.020" thick CRODON wear surface on ¼" base of 400 Brinnel, through hardened material, improved resistance to penetration by 30%.
   
   In ball drop testing, as expected, standard CRODON wear plate would dent just as normal carbon steel would dent. However, the bond of the CRODON wear surface was not compromised, regardless of the force applied. CRODON Plus wear plate was compared to unprotected through hardened AR400 material. The results showed at least an 8 fold improvement in resistance to initial indentation without compromising performance for either the CRODON wear surface or the base material.
   
   We also tested chromium carbide weld overlay material for impact and found that catastrophic failure was the primary mode on failure and that the force required was unpredictable. If the ball fell in the "wrong " place, it would fail under very low force. Our conclusion was that chromium carbide overlays are not appropriate for moderate or high impact conditions.

Conclusion:
We will continue to "push the envelope" in our field and bench testing. We know that in some conditions other materials will perform better but that in a wide range of applications CRODON wear plate is the best alternative on the market.