DLC coating - \"plain clothes\" for automobile wiper

Wiper is an important device of automobile, which plays a vital role in safe driving.

A good wiper must have the characteristics of heat resistance, cold resistance, acid and alkali resistance, corrosion resistance, can fit the windshield, reduce the burden of the motor, low noise, strong water displacement, soft quality, and can not scratch the windshield, and can make your vision clear.

The car wiper is made of rubber. Untreated rubber is easy to age and wear, and its color is easy to distract attention. Long-term use will cause dizziness and visual fatigue. And it is not resistant to dirt. It gradually turns yellow over time. Its appearance and performance are greatly reduced. So in 1915, people began to use the process of high-temperature condensation of carbon and hydrocarbons to make the rubber appear pure black like ink.

After adding carbon black (powder), the heat generation, wear resistance and rolling resistance of rubber decrease, the tensile strength and elongation stress increase, and the tear strength decreases. The durability is improved. However, long-term use will still harden, age and crack, and carbon black has a stronger ability to absorb impurities. The adsorbed sand and dust will not only grind the windshield, but also cause the wiper to jump abnormally and swing irregularly, thus damaging the wiper itself.

Figure 1: The wiper rubber strip absorbs impurities, aging and fracture

The wiper must ensure sufficient wetness to have good toughness to maintain the tightness of contact with the windshield. This can be effectively ensured by applying a film layer on the rubber strip surface of the wiper. The following three figures show the three states of rubber processing.

Figure 2. Uncoated light gray adhesive strip with rough surface and easy to absorb dust

Figure 3. The surface of the black adhesive strip with carbon black is still rough and astringent, easy to absorb dust

In Figure 4, new platinum is directly PVD coated with black film on the basis of Figure 1, and the surface is moist without dirt.

As shown in the figure above, the effect of PVD coating is significantly better than the former two, which is due to the characteristics of DLC film.

1) The surface of DLC film is generally smooth and clean, and the dense film structure forms the effect of solid lubrication, forming good hydrophobic and water displacement performance;

2) With ultra-low friction coefficient, the colloidal surface has been modified to resist abrasion, and the friction coefficient has been reduced by 3 times, effectively reducing friction and vibration during brushing, and reducing or even eliminating noise;

3) It has good adhesion resistance and anti-seize property, and also has adhesion resistance to non-ferrous metals, plastics, rubber, ceramics, etc. to reduce foreign matter adsorption;

4) , with high elastic modulus, the coating is still tightly bonded even if it is bent or twisted;

Figure 5. Bending and twisting state of DLC coated rubber strip

5) It has extremely high chemical stability and excellent acid and alkali corrosion resistance;

6) , good weather resistance. DLC film has ultra-high thermal conductivity and resistance to high and low temperature impact.

7) , high hardness, not easy to damage;

8) , weakening the influence of ultraviolet rays;

9) , dark and bright surface, low-key and elegant, highly decorative, while preventing glare;

10) The coating is environmentally friendly and pollution-free;

To sum up, DLC coating has excellent mechanical, chemical, electrical, chemical and mechanical properties, which can greatly extend the service life of rubber strips, and is an ideal "plain clothes" for automobile wiper.

Some pictures are from the network.

(Contributed by zpp)