Surface Science and

Nano-Tribology Laboratory

   

Sponsored by Exatec Automotive Window System, to improve our understanding on a coating/substrate system, we have studied the effects of physical properties of substrate, hard-coating thickness, and adhesion between the coating and substrate on the micro indentation hardness (MIH) and micro mar resistance (MMR).

  • The Substrate Effect

    In a coating/substrate system, the influence of substrate becomes significantly important at the penetration depths h > 10% of the film thickness. To examine the influence of substrate elastic properties on the mechanical behavior of the thin-film /substrate systems, the plasma coating was deposited on polycarbonate (soft substrate) and glass (hard substrate), respectively.

  • The Thickness Effect

    To examine the influence of hard-coating thickness on the mechanical behavior of the thin-film /substrate systems, we choose three different coating thickness: 1.8mm, 2.6mm, and 3.5mm, respectively.

  • The Influence of Adhesion

    To examine the influence of adhesion between the coating and substrate on the mechanical behavior of the thin-film /substrate systems, three Plasma (4mm)/Siloxane/Polycarbonate samples were pretreated in different way. Though there are no significant difference among the their MMR values under the same normal force, their wear modes are different.

 

1. The Substrate Effect

Sample-a: Plasma (2.6mm)/Siloxane/Polycarbonate

Sample-b: Plasma (2.6mm)/Siloxane/Glass

Fig. 1.a. MIH (MPa) v.s. Normal Force (mN)

Fig. 1.b. MMR (GPa) v.s. Normal Force (mN)

 

2. The Thickness Effect

Sample-a: Plasma (1.8mm)/Siloxane/Polycarbonate

Sample-b: Plasma (2.6mm)/Siloxane/Polycarbonate 

Sample-c: Plasma (3.5mm)/Siloxane/Polycarbonate

 

Fig. 2.a. MIH (MPa) v.s. Normal Force (mN)

 

Fig. 2.b. MMR (GPa) v.s. Normal Force (mN)

 

Fig. 2.c. Threshold Cracking Force

 

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Sample-a: Plasma (4mm)/Siloxane/Polycarbonate

Sample-b: Plasma (4mm)/Siloxane/Polycarbonate

Sample-c: Plasma (4mm)/Siloxane/Polycarbonate

    Sample-a, b, and c were pretreated in different way. Though there are no significant difference among the their MMR values under the same normal force, their wear modes are different.

Fig. 3. Different Wear Modes

 

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Fig. 4. Wear Classification