Nickel Coating Improves Tool Life
THE MAGAZINE DEVOTED TO NICKEL AND ITSAPPLICATIONS
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A PHOTO MICROGRAPH of the leading edge of a stone cutting tool. Visible are industrial diamonds embedded in a metal matrix which consists of a proprietary nickel alloy and an intermediate layer. |
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Better abrasion resistance key to making rock-cutting tools last longer. By Virginia
Heffernan
Nickel magazine, March, 2004 -- A new nickel-based coating for diamonds is improving
the performance and lengthening the life of stone-cutting tools.
The unique design requirements of diamond tools used to cut stone and concrete make them vulnerable to wear and tear. The tools require soft metal bonds for free cutting, but these same bonds - containing a high percentage of copper or copper alloys - are susceptible to erosion and poor diamond adhesion. Many of the diamonds are lost before the tool has reached the end of its useful life.
The MBS SB diamond developed by Ohio-based GE Superabrasives overcomes this flaw with an innovative double coating design consisting of a nickel alloy and an intermediate layer. The alloy coating improves adhesion between the diamond and the soft metal matrix, while the intermediate layer acts as a glue between the coating and the diamond.
"Historically, soft-bond diamond tools have relied on uncoated MBS diamond as the abrasive," says Shridar Kompella, an engineer for GE Superabrasives. "Uncoated diamond, however, does not interact with the copper-alloy in the matrix upon processing and is prone to popping out prematurely. The SB coating enhances retention of the MBS SB diamond in the bond and helps to ensure the optimal use of a diamond."
GE considers the composition of the nickel alloy and intermediate layer proprietary.
Coating diamonds for improved performance is a relatively recent technical advance designed to address industry demand for better diamond retention and longer tool life. Before coatings were developed, the popping out of diamonds was a regular occurrence caused by poor chemical bonding between the diamond and the metal matrix, chemical attack during the sintering, and/or fractures resulting from inherent weaknesses in the diamond.
The most common metal coatings for diamonds are chromium and titanium. These metals resist chemical attack and protect the diamond's strength and surface. They also have a high level of metallurgical compatibility with the common bond matrix elements, such as cobalt, used in many diamond tools.
The nickel alloy coating is different because it works specifically with soft metal bonds used to enhance
free-cutting capabilities (trimming marble, granite or ceramic tiles, for instance). For this application,
nickel provides a strong metallurgical compatibility with the copper matrix and abrasion resistance in the
vicinity of the diamond. GE Superabrasives claims the marked increase in diamond retention results in
significantly longer tool life, lower power consumption and superior cutting ability.
Virginia Heffernan is a Toronto-based freelance writer.
PHOTOS: GE Superabrasives
Carmen Kassing |
