Fretting tribological performance of DLC, TiAlN and DLC/TiAlN coatings deposited on carburized 18CrNi4A steel

To improve the fretting wear performance of 18CrNi4A steel, DLC, TiAlN and DLC/TiAlN coatings were deposited on the surface of carburized 18CrNi4A steel, respectively. The microstructure morphologies, chemical compositions, and mechanical properties of these coatings were evaluated. The fretting tribological properties of pad/flat contact pairs for carburized 18CrNi4A steel, DLC, TiAlN and DLC/TiAlN coatings were investigated in different lubricant environments including dry sliding and #RIPP 7254 aviation grease. The results show that DLC, TiAlN and DLC/TiAlN coatings deposited on the carburized 18CrNi4A steel surface can improve surface roughness, hardness, fracture toughness and resistance to plastic deformation. DLC, TiAlN and DLC/TiAlN coatings deposited on the surface of carburized 18CrNi4A steel can make the surface of the substrate have excellent fretting wear properties. DLC and DLC/TiAlN coatings have lower coefficient of friction and better fretting wear resistance than TiAlN coatings in dry sliding condition, and DLC/TiAlN coatings have the lowest wear rate in #RIPP 7254 grease lubrication condition. In addition, the wear mechanisms of carburized 18CrNi4A steel, DLC, TiAlN and DLC/TiAlN coatings in dry sliding and #RIPP 7254 aviation grease conditions were analyzed.

Spontaneous inversion of the submicron ceramic layer deposited on steel and the copper droplet positioned on their top (case of ceramic poorly wetted by liquid Cu)

In this paper, 50 … 680 nm thick AlN-Al2O3 coatings are deposited by magnetron sputtering on the surface of a steel substrate and a piece of copper is melted on top of the ceramic. Upon heating the ceramic layer is cracked, and the phase inversion of the two top phases from steel/ceramic/copper configuration to the steel/copper/ceramic configuration takes place within 30 s of liquid time of copper. This phase inversion process is accompanied by a Gibbs energy change of about − 1.78 J/m2, due to good wettability of solid deoxidized steel by liquid copper in contrary to poor wettability of the ceramic by the copper. When copper is melted on AlN-Al2O3 coating with its thicknesses smaller than a critical value of about 170 ± 60 nm, liquid copper droplets hanging down into the cracks within the ceramic reach the solid steel surface at the bottom of the cracks, thus the flow of Cu down along the cracks is enabled. However, when copper is melted on AlN-Al2O3 with its thickness larger than the critical value of 170 ± 60 nm, Cu first forms a non-wetting droplet on top of the ceramics, and only after a certain incubation time it starts flowing down the cracks. This incubation time was found to depend linearly on the thickness of the ceramic, as cracks are filled from the bottom upwards by liquid copper via the evaporation–condensation mechanism. By the end of the process, the steel/copper/ceramic configuration is further stabilized by gravity. Graphical abstract

Experimental study of electromechanical measurement, surface analysis and corrosion inhibition of mild steel in 1M HCL by Schiff’s bases (SBs)

Potentiodynamic polarization measurements indicate that SBs acts as mixed type corrosion inhibitors. the morphology of the mild steel surface is investigated by scanning electron microscopy (SEM) and the surface composition was evaluated using energy-dispersive X-ray Spectroscopy (EDX) to show the presence of SBs on the mild steel surface in 1M HCL. The present study, three Schiff’s bases (SBs) namely 2 (2-hydroxybenzylideneamino) heptanedioic acids, 2 (4-dimethylamino benzlideamino) heptanedioic acids and 2 (4hydroxy-3-methoxybenzylideneamino) heptanedioic acids were synthesized. Using weight loss, potentiodynamic polarization and electromechanical impedance spectroscopy (EIS) techniques for corrosion inhibition properties on mild steel in 1M HCL has been investigated. The adsorption of SBs on the mild steel surface contains Langmuir adsorption isotherm. Here kinetic and thermodynamic parameters also determined to describe the mechanism of adsorption in relevance. The main object of this presentation is experimental study of the inhibiting action of synthesized Schiff’s bases of aldehydes containing nitrogen, oxygen and aromatic rings and Glutamic acid.

Potensi Ekstrak Daun Pepaya sebagai Inhibitor Korosi dalam Media Asam Klorida pada Baja ST37

Corrosion is a decrease in the quality of a metal material caused by a reaction with the environment. Reducing the corrosion rate on steel can be done by adding an inhibitor. Papaya leaf extract (Carica papaya.L) can be used as a corrosion inhibitor by immersion method. The effect of inhibitor on corrosion rate had been studied using weight loss method, potentiodynamic polarization method, and observation of steel surface using photooptic. It was found that corrosion rate decrease with increase concentration of papaya leaves extract. The highest inhibiton efficiency is 87.8% in 0.2 M hydrochloric acid with 2% concentration of papaya leaves extract. Potentiodynamic polarization method showed that papaya leaves extract decrease corrotion current. Inhibiton efficiency reached 81.58% in 2% extract concentration in which corrosion current decrease from 0.0266 mA/cm2 to 0.0049 mA/cm2. Analysis of photooptic showed that there is difference on steel surface corroded in hydrochloric acid with inhibitor and without it.

The properties of AISI 316L steel after surface treatment with Ti surface alloy and a-C:H:SiOx coating

The paper presents the research results of corrosion and mechanical properties of the AISI 316L stainless steel after the surface treatment. This treatment includes the formation of the titanium-based surface alloy provided by the low-energy high-current electron beam. The obtained surface alloy used as an underlayer, is then coated with the a-C:H:SiOx film using the PACVD method. It is shown that such a combined treatment of the steel surface improves its corrosion resistance, i. e., reduces the current density from 110-7 to 910-10 A/cm2 and corrosion rate from 1.110-3 to 9.310-6 mm/year. The resulted modified steel surface possesses high mechanical and tribological properties