High Scratch Resistance Research Articles

Wear resistant coatings for contact recording applications

To achieve low stiction and low interface wear in contact recording, a hard coating having a high hardness, elastic modulus, and scratch resistance is required. In this study, mechanical and tribological characterization of carbon coatings deposited by various deposition techniques and SiC has been carried out. Based on nanoindentation and microscratch studies, it is concluded that cathodic arc carbon coatings exhibit the highest hardness, elastic modulus, scratch resistance, and wear resistance.

Coatings for mechanical and chemical protection based on organic-inorganic sol-gel nanocomposites

The sol-gel process opens the possibility of combining inorganic and organic units on a molecular or nanosized level. The flexible chemical approach of tailoring inorganic structures as well as organic polymeric structures in combination with the new concept of incorporation of nanoscaled metal oxide particles opens the possibility of achieving new multifunctional materials like extremely high scratch resistance, antisoiling properties, antifogging properties and corrosion-inhibitant coatings on metals.

PLASMA ION-ASSISTED EVAPORATIVE DEPOSITION OF SURFACE LAYERS

Vacuum thin film processes are becoming increasingly important in modern high technology because of their possible use in changing the surface properties over a wide range while maintaining the properties of the bulk material. The requirements for temperature stability and low absorption and scattering losses are becoming ever more stringent for thin films used in optical applications. Furthermore, synthetic substrate materials are more and more used for ophthalmic lenses as well as for high precision optical components. Especially important is the fact that a rather soft substrate material can be covered with a hard surface layer, thus providing a high scratch-resistance without the brittleness of common hard materials. In principle, the process technology for vacuum deposition of thin films can be subdivided in physical vapor deposition (PVD) (evaporation, sputtering) and chemical vapor deposition (CVD) with subgroups thermal CVD, PECVD, and photo CVD. Evaporation, the classical method of producing thin coating layers, using the technique of electron beam evaporation provides a comparatively high rate of deposition. The coating of sha,ped or two-dimensional optical substr+ites also uses evaporation for reasons of better film distribiItion. Evaporation processes under vacuum require an arrangement of an evap­ oration source and the substrate to be covered such that the evaporated

Scratch resistant low friction/low surface energy coating for silicon substrate

AbstractA smooth, ultrathin film of a polydimethylsiloxane (PDMS) on a silicon substrate has been prepared by spin‐coating. This film gives a 0.06 dynamic coefficient of friction against paper, the lowest value ever reported for polymer–paper sliding pairs. The value is only about one‐third of the coefficient of friction (0.21) between polytetrafluoroethylene and paper. The coating is not scratchable by sliding a stainless steel stylus over the surface with a pressure greater than 3.6 × 1010 dyn/cm2. The film displays a surface tension of 20.5 dyn/cm. It is stable in water and propylene glycol. The film is an effective and durable solid lubricant. The surface characteristics of a spray‐coated PDMS and a plasma‐copolymerized thin film of perfluoropropane and 3,3,3‐trifluoropropylmethyldimethoxysilane have also been investigated. Both films show much lower scratch resistance, weaker adhesion to the silicon substrate, and higher friction. The plasma film yields the same surface tension as the spin‐coated PDMS. Its surface energy, however, increases after soaking in water or propylene glycol. The exceptionally low friction and the unusually high scratch resistance of the ultrathin film of PDMS are attributed to the absence of deformation and tearing components and a low adhesion components in the sliding friction mechanism.

Protective Coatings for Stained Glass

AbstractThe protection of glass against water-initiated chemical corrosion is a significant problem. Presently, organic polymers and inorganically modified polymers are being used to protect art glass. However, the service life and durability of these coatings are not entirely satisfactory. Oxide coatings would offer much greater resistance to water penetration. Water permeability through a polymer coating is some ten orders of magnitude larger than that through an oxide coating. This, coupled with a higher scratch resistance, makes oxide coatings promising candidates for the protection of stained glass. Methods to deposit an oxide on glass at relatively low temperatures include sol-gel processing and vapor deposition. This paper compares the performance of different oxide and non-oxide coatings and presents methods for the deposition of oxide coatings at low temperatures.

Characterization of plasma-sprayed WC-Co coatings

Plasma-sprayed WC-Co coatings are used to combat wear and erosion. As-sprayed and heat-treated WC-Co coatings on mild steel substrates were characterized. The use of ArH 2 and ArHe gas mixtures was found to influence the loss of carbon and thereby the phases present in the coating. Quantitative X-ray diffraction was used to determine the amount of WC, W 2C and tungsten in the coatings. Heat treatment of the coatings at 1373 K for 1 h in vacuum resulted in the formation of Co 3W 3C in the coating and Co 6W 6C at the interface. The relative adherence of the coatings was evaluated by a three-point bending test. The wear properties were determined using a laboratory scratch tester. The heat-treated coatings were found to have a higher adherence and a higher scratch resistance.

Exceptional hardness and corrosion resistance of Mo5Ru3and W3Ru2films

Films of MO5Ru3 and WgRu2 prepared by sputtering on hot sapphire substrates exhibit interesting properties. The films are among the hardest known electrical conductors and show Khoop hardness values comparable to sapphire. They exhibit high resistance to most common etchants (particularly acid etchants), have high scratch resistance, and have excellent adhesion to the (sapphire) substrates. The temperature coefficient of electrical resistivity can be made either negative, positive, or zero by varying the substrate deposition temperature. Reflectivity measurements from ultraviolet to infrared are also reported to assess their possible use as reflecting surfaces.

Mercury-vapor lamp for inspecting translucent products : Anon. ( Electr. World, lxiv, No. 2, 78)

In order to reduce the thermal expansion coefficient (TEC) to make it fit high scratch resistance glazes, which have lower TEC values, bone china body is reformulated. This is done by reducing the amount of bone ash, which is responsible for the formation of a crystalline phase of β-tricalcium phosphate (β-TCP) with a high TEC value and adding prefired anorthite materials, which has a lower TEC value, in the body.Fired samples of reformulated bone china show a bluish-green tint due to iron impurities. When about 5 wt.% of ZnO was added to the reformulated bone china bodies this bluish-green tint was removed and the degree of the whiteness of reformulated body was again become similar to commercial bone chinas. The cause and elimination of discolouration of reformulated bone china have been investigated. ZnO containing reformulated bone china bodies develop zinc-spinel (gahnite, ZnAl2O4) crystals, which are the reason for the increasing whiteness of samples by incorporating iron ions into the spinel structure.