Diamonds have always been a girl’s best friend. Now, one materials company says they could be an engineer’s best friend too. Bekaert Advanced Coating Technologies says its diamond coatings can help engineers solve mold fill, mold release, abrasive wear, corrosion, and downtime problems. The reason: their combination of wear protection, improved release, and corrosion resistance.
The company Michael McCabe says diamond-like carbon coatings (DLC) and diamond-like nanocomposite (Dylyn) coatings increase wear resistance, corrosion protection, and surface lubricity. He says that the coatings have a low surface energy similar to that of Teflon[R], but with a hardness greater than carbide or Titanium Nitride. In a special white paper on the products, he writes that the plastic additives, to increase toughness and resist mildew, add fire resistance. The hardness range, from 10 to 25 GPa, increases surface wear resistance of all plastic mold tool materials.
“The coating takes care of wear,” McCabe says, “so engineers can optimize material for heat removal and improve cycle time.” He says one of the company’s customers doesn‘t even use lubricants anymore.
During molding, he asserts, the coatings can promote better release of parts, which affects productivity. The coatings’ coefficient of friction ranges from 0.05 to 0.1 vs. 0.7 for steel. Surface energy ranges from 25 to 35 mNm.
McCabe writes that the coatings are dense and exhibit little porosity, which
accountgs for the corrosion protection. Still, he says, coatings alone will
never be the complete answer. Design of the mold, choice of tool materials, and
preparation of the mold prior to coating are important.
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DLC and Dylyn coatings are deposited using a PACVD (plasma-assisted
chemical vapor deposition) process, at deposition temperatures below 200°C
(400°F), enabling both electrically conductive and non-conductive
substrates to be coated
homogeneously.
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