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Under optimized operating parameters, a hard and wear resistant ( Ti,Al)N film is prepared on a normalized T8 carbon tool steel substrate by using pulsed high energy density plasma technique. Microstructure and composition of the film are analysed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy and scanning electron microscopy. Hardness profile and tribological properties of the film are tested with nano-indenter and ring-on-ring wear tester, respectively. The tested results show that the microstructure of the film is dense and uniform and is mainly composed of ( Ti,Al)N and AlN hard phases. A wide transition interface exists between the film and the normalized T8 carbon tool steel substrate. Thickness of the film is about 1000 nm and mean hardness value of the film is about 26GPa. Under dry sliding wear test conditions, relative wear resistance of the ( Ti,Al)N film is approximately 9 times higher than that of the hardened T8 carbon tool steel reference sample. Meanwhile, the ( Ti,Al)N film has low and stable friction coefficient compared with the hardened T8 carbon tool steel reference sample.

Nano-crystalline diamond films have been prepared on glass substrate in argon and methane environments by microwave plasma chemical vapor deposition. The suitable processing parameters are methane concentration 3% in argon; total deposition pressure 13.3 kPa; substrate temperature 500°C heated by plasma. In this film, the grain size is

Pulsed high energy density plasma has been used to deposit aluminum nitride films on the surface of the 1Cr18Ni9Ti stainless steel (∼0.1% C, ∼18% Cr, ∼9% Ni, ∼0.8% Ti). The formed films are composed of nanocrystalline-structured aluminum nitride phase, whose crystal sizes are about 10 nm. Transition areas are formed across the film to the substrate and strengthen the adhesion between them. The nanocrystalline-structured aluminum nitride films contribute to the improvement of the corrosion resistance of the modified stainless steel, whose corrosion rate has been reduced by about ten times compared with that of the unmodified stainless steel.

A wear resistant Ti5Si3/NiTi composite coating was fabricated on a substrate of a titanium alloy by plasma jet cladding using Ni-Ti-Si elemental powder blends. The microstructure, microhardness and wear resistance of the coating were evaluated. The result shows that the plasma jet clad composite coating has a rapidly solidified microstructure consisting of blocky primary Ti5Si3 and the inter-blocky Ti5Si3/NiTi eutectics and is metallurgically bonded to the titanium substrate. The composite coating has high hardness and excellent wear resistance under the dry-sliding-wear test condition.

Plasma electrolytic oxidation (PEO) coatings are prepared on aluminium with graphite powders added into the electrolyte. The scanning electron microscopy (SEM) coupled with an energy dispersive x-ray analysis system (EDX) is used to characterize the surface and the cross-section morphologies of the coatings. The electrochemical impedance spectroscopy (EIS) is used not only to evaluate the corrosion resistance but also to analyse the structure of the coating. Results show that graphite powders are embedded in the PEO coating. The corrosion resistances of both the inner barrier and the outer porous layer are greatly improved, and the EIS could give some valuable detailed information about the coating structure.

Under optimized operating parameters, a wear and corrosion resistant Cr3Si/γ-Fe composite coating is fabricated on a normalized 0.45% carbon steel substrate by using the plasma transferred arc (PTA) cladding technique with Fe-Cr-Si elemental powder blend as the precursor material. Microstructure, microhardness, dry-sliding wear resistance and electrochemical corrosion characteristic of the coating are evaluated. Test results show that the composite coating is mainly composed of primary Cr3Si dendrites and the interdendritic supersaturated iron-base solid solution γ-Fe. Between the Cr3Si/γ-Fe composite coating and the normalized 0.45% carbon steel substrate, there is a narrow metallurgical bonding zone. The Cr3Si/γ-Fe composite coating exhibits high microhardness, excellent wear and corrosion resistance under test conditions.

Plasma electrolytic oxidation (PEO), also called micro-arc oxidation or anode spark deposition, is a novel technique to produce hard ceramic coatings on metals, such as aluminum, titanium, magnesium and their alloys (called by a joint name of valve metals). Up to now, almost all the researchers focused attention on the PEO process for samples of regular shapes such as cubes, discs or rods, and no one paid attention to the irregular samples such as tubes. In this work, the PEO behavior of aluminum tubes was investigated. The potential difference, which had a liner relation with the coating thickness inside the tube, was measured. A central axial accessorial electrode was used to eliminate the effect of potential decay inside tubes, which was effective for obtaining axially uniform coating on the inner surface of the tube.

In this paper, composite coating (about 400 μm thick) was prepared by SHS plasma spraying technology using micro-dimensional Fe2O3-Al composite feedstock, which was fabricated by mechanical glomeration. The composition and microstructure of the coating were analyzed by X-Ray diffraction, scanning electron microscopy and transmission electron microscopy. Meanwhile, the microhardness, fracture toughness and wear resistance were also measured. It shows that the skeleton of the coating is mainly composed of nanostructured FeAl2O4 and Al2O3, and the dispersed phase is nanosized Fe. The composite coating possesses satisfactory microhardness of about Hv870. Compared with conventional alumina coating, the fracture toughness and wear resistance of composite coating are increased by one and 1.5 times, respectively.

Metallurgically bonded Al2O3 ceramic coating was prepared on steel surface with the combined method of arc spraying and electrolytic plasma processing. The composition and microstructure of the ceramic coating were analyzed by x-ray dif fraction, scanning electron microscony and EDS. The corrosion resistance and wea r resistance of the ceramic coating were measured. The results show that the cer amic coating is compact and mainly composed of α-Al2O3, γ-Al2O3, θ-Al2O3 and a little of a morphous phase. The duplex coating shows favorable corrosion resistance and wear resistance properties.

The basic idea of the reactive plasma spray (RPS) was presented. The TiN coating was successfully deposited on Q235 steel substrate by using the gas_tunnel plasma spray gun via RPS. Micro_hardness of the TiN coating under different loads has been measured, revealing an obvious indentation size effect, and a weak work_hardening effect. XRD, TEM and HRTEM were employed to analyze the prepared coating samples. Results obtained show that nanocrystalline TiN coating has been achieved via RPS, which is composed of TiN crystals of about 57—70nm in diameter and the amorphous TiN.

Smooth, densie and uniform nano-crystalline diamond-like-carbon (DLC) film is deposited on an optical glass substrate by pulsed high energy density plasma(PHEDP) gun charging in nitrogen atmosphore. Scanning electron microscope, Raman spectra and EMSA show that, the grain size of the DLC film is less than 20nm; there are a number of nitrogen atoms and nano-crystalline diamond in the DLC film. The sheet resistance of this film is larger than 109Ω/sq. When the change voltage is lower and charge distance is longer, the deposited film is loose. Theoretic analysis show that, at higher charge voltage, the deposited grain is larger, with longer charge distance, the collision force between deposition grain and substrate is weaker. The theoretic results are in agreement with the experimental conclusion.

As a novel inner surface processing method, grid enhanced plasma source ion implantation (GEPSII) method can realize uniform inner surface ion implantation of a metal tube and metal binary compound can be produced. In the experiment, three 0.45% carbon steel (45-steel) work pieces were axially put on the inner surface of the tube, and golden titanium nitride (TiN) films were produced on the work pieces by GPSII. Structure analysis shows that the TiN films have the preferred crystal faces (111) and (200), and the depth of the films is about 20 nm with partial embedding in the substrate. Analysis on the electrochemistry corrosion, hardness and friction of the work pieces indicates that the surface property of the 45-steel has been greatly improved by the protective TiN film, and very good axial uniformity has been obtained.