Improved surface properties of AISI-420 steel by Ti[sbnd]C based coating using graphite cathodic cage with titanium lid in plasma deposition

Enhanced wear and corrosion resistance of AISI-304 steel by duplex cathodic cage plasma treatment

Titanium nitride (TiN) is a good choice for the improvement in surface hardness of high-speed steel. Unfortunately, it has low adhesion with substrate and exhibits high friction coefficient; as a result it does not provide sufficient protection against sliding wear in metal-to-metal contact. The adhesion problem can be removed by nitriding process, whereas friction coefficient can be reduced by solid lubrication coating. In this study, an attempt is made to synthesize TiN hard coating as well as solid lubrication coating of molybdenum disulfide (MoS2) using magnetron sputtering, along with substrate pre-treatment by cathodic cage plasma deposition using titanium cathodic cage. The cathodic cage plasma nitrided sample exhibits significantly higher surface hardness, which reduced by solid lubrication coating. The nitrided sample depicts the presence of iron nitrides, TiN and nitrogen diffused martensite phases, whereas coated samples shows the presence of MoS2 and TiN phases. The friction coefficient and machining temperature are dramatically reduced by lubrication coating. This study recommends that the use of cathodic cage plasma nitriding using titanium cathodic cage is beneficial for improved surface hardness, and addition of solid lubrication coating is beneficial for reducing the coefficient of friction and machining temperature by scarifying hardness. As, both the systems are already proven to be appropriate for industrial-scale uses, thus results from this study can be applied for industrial-scale application.

Corrosion is an event of metal degradation due to reaction to the environment. One way to prevent corrosion is to use inhibitors. This inhibitor can prevent the rate of corrosion of metals by providing a coating on the metal of an extract of organic material having N, S, O, P atoms with the aid of solvents and in the heat process. This study aims to determine the effect of inhibitor material variations on corrosion rate on iron, and to know which inhibitors are more efficient to prevent the rate of corrosion. The research method used is experimental method that is weight loss with the result of data analysis using analysis of variance in software minitab 17. The result of research shows that there is influence to the variation of inhibitor material on the decrease of corrosion rate. From the research results obtained data which inhibitor more efficient to prevent corrosion, tobacco leaf has average corrosion rate of 0,000049 gram / cm2 hour and efficiency of equal to 43,40%, while for coffee decrease of average corrosion rate is 0, 000158 gram / cm2 hour and its efficiency is 23.26%, while the clove cigarette has an average corrosion rate of 0,000094 gram / cm2 hours and efficiency 33,34%. We can see that the most efficient inhibitor is from tobacco extract with the lowest corrosion rate and the greatest efficiency.

Martensitic stainless steels (MSSs) have been widely used in the manufacture of turbine blades, surgical instruments, and cutting tools because of their hardness and corrosion resistance. The MSSs are usually tempered at a temperature no higher than 250 °C after quenching to avoid the decline in the hardness, strength, and corrosion resistance of the steels. However, some short-time thermal shocks are inevitable in processes like welding, water grinding, laser marking, etc., in the manufacturing of kitchen knives, all of which may have negative effects on the mechanical properties and corrosion resistance. The effects of these short-time thermal shocks have rarely been studied. In this paper, the martensitic stainless steel 5Cr15MoV (X50CrMoV15 is European Standards) was selected to be tempered at the sensitization temperatures (480 to 600 °C) for a series of times (0.5 to 128 min) after quenching, and the microstructures, hardness, and corrosion resistance of the steel after tempering were investigated. It was shown that the variation in hardness and corrosion resistance of the 5Cr15MoV steel could be divided into four stages over time during tempering at the sensitization temperatures. The hardness of steel was found to increase at first and then decrease with time; accordingly, good corrosion resistance was retained in the initial few minutes of tempering, which then deteriorated fast. The variation in hardness and corrosion resistance of the 5Cr15MoV steel is related to the diffusion of C and Cr atoms at different tempering temperatures. The mechanism of the mechanical properties and corrosion resistance variation caused by the diffusion of C and Cr atoms during tempering at the sensitization temperatures was also discussed.

Zink anodes are very importantfor reducing the corrosion rate on underwater surface area of hull plates. Zink anodes are affixed to parts of the vessel that are prone to seawater corrosion. This study aims to find out how much influence the installed current has on the corrosion rate by analyzing the data on the use of zink anodes in the field and the data on the use of zink anodes as a result of calculations so that the use of strong currents installed according to the need will reduce the rate of corrosion. To see the strong influence of current on the rate of corrosion, it takes data on the corrosion rate of the last 5 years from 9 vessels and also the number of zink anodes used each year. From the graph of the results of the calculation of strong current according to the theory and the results of the use of zinc anodes on nine vessels, the results obtained it is clear that the installed current strength must meet the needs of each vessel because it will affect the decrease in corrosion rate. On vessel No.3, an excess current strength of 0.539Amp to 1,386 Amp, a decrease in corrosion rate reaching 0.0317 mm/year in the 5th year. On vessel No. 4, an excess current strength of 0.444 Amp to 1.822 Amp there is a decrease in corrosion rate reaching 0.0138 mm/year in the 5th year. On vessel No. 9, an excess strong current of 4,894 Amp to 5,793 Amp there is a decrease in corrosion rate reaching 0.0371 mm/year in the 5th year.

Nine ASTM A588 low-alloy weathering steels representing three levels of silicon and nickel were prepared by induction melting and hot rolling in the laboratory. Corrosion tests were conducted for eleven years at four atmospheric sites which included industrial, rural, and marine locations. The results were fitted to kinetic equations of the form, C= AtB, where C is the corrosion loss, t is time, and A and B are constants in accord with Method 1 of ASTM G101 “Standard Guide for Estimating the Atmospheric Corrosion Resistance of Low Alloy Steels.” Both silicon and nickel are shown to have a beneficial effect on the corrosion resistance of A588 weathering steel. For silicon, on average, each 0.1% increase results in a 4% decrease in corrosion loss after 11 years, a 6% decrease in corrosion rate after 11 years, and a 12% increase in the time to reach a 10-mil(250μm) penetration. For nickel, each 0.1% increase results in a 4% decrease in corrosion loss after 11 years, a 7% decrease in corrosion rate after 11 years, and a 15% increase in the time to reach a 10-mil (250(μm) penetration. By way of comparison, Method 2 of ASTM G101 predicts a 2% increase in the corrosion index for each 0.1% increase in silicon or nickel.

The investigation of wear and corrosion behavior of plasma nitrided DIN 1.2210 cold work tool steel

Corrosion behaviour of surgical implant materials: I. effects of sterilization

Effect of yttrium on the corrosion of AB 5-type alloys for nickel–metal hydride batteries

The effect of N content on the microstructure and wear resistance of 4Cr13 corrosion-resistant plastic mold steel were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tribometer. The results showed that the influence mechanism of nitrogen on the hardness of the test steels responded to the changes in the quenching temperature. When the quenching temperature was below 1050 °C, the solid solution strengthening of N played a dominant role as a wear mechanism, and as the N content increased, the hardness of the steel increased. When the quenching temperature was higher than 1050 °C, N increased the residual austenite content, resulting in a decrease in hardness. The addition of N reduced the optimal quenching temperature of the test steels. The N addition promoted the transformation of large-sized M23C6 to M23C6 and fine Cr2N, resulting in an increase in the hardness of the test steels. The influence on the wear resistance of the experimental steels differed according to the varied N contents. The addition of 0.1% N delayed the precipitation of large- sized particles in the second phase, increased the hardness of the steel, and reduced the degree of wear. However, an excessive addition of N (0.18%) led to the excessive precipitation of the second-phase particles, and the second-phase particles then gradually flaked during the wear process and continued to participate in the wear process as third-body abrasives, reducing wear resistance.

Improved wear resistance of AISI-4340 steel by Ti–Nb–C–N and MoS2 composite coating by cathodic cage plasma deposition

Corrosion is a scourge to civilization and is chewing deep into our metal world. Corrosion process obeys well known laws of electrochemistry, thermodynamics and many variables that influence the behavior of metals. Anaerobic microbial influenced corrosion of oil pipeline steel inhibitions with Manniphytonfulvum mull leaves ethanol extract and aqueous extract each and respectively was studied using gravimetric and media absorbance examination techniques. The test organism Desulphurvibro species were isolated from corroded pipeline steel immersed in crude oil and water mixture sample, collected from Agip drilling site in AhodaPorthacourt, Rivers state, Nigeria. Postgate medium was used for the isolation of the organism, and the coupons used for the study were prepared from the rusted pipeline steel. Absorbance results of the media containing the plant extract (ethanol extract and aqueous extract each) are lower than the absorbance result of the blank medium (without the extract). The decrease in absorbance is suggested to be, as a result of inhibition of the growth of sulphate reducing bacteria (Desulphurvibro species) by the plant extract in the media, which leads to fewer bacteria that obstructs the passage of light through the medium. Gravimetric results showed decrease in weight loss and corrosion rate of the pipeline steelin the plant extract containing media, from the weight loss and corrosion rate of the steel immersed in the blank medium (without extract). The decrease in corrosion rate was more pronounced as the concentrations of the extracts in the media increased from 10 mg/ml to 500 mg/ml. Inhibition efficiency of the plant extract increased as concentrations of plant extract increased. Meanwhile, increase in inhibition efficiency was found to be more susceptible in ethanol extract than aqueous extract. The microbial influenced corrosion is inhibited by Manniphytonfulvum mull extract by both inhibition of the growth of the sulphate reducing bacteria cells and adsorption of the plant extract molecules, on the metal surface forming a barrier between the metal and the invading bacteria. The adsorption of the plant extracts both ethanol extract and aqueous extract best fitted into Langmuir adsorption isotherm. It is concluded that Manniphytonfulvum mull leaves ethanol and aqueous extracts each and respectively, inhibited the growth of sulphate reducing bacteria and corrosion of oil pipeline steel caused by the bacteria in anaerobic medium.

CO2/H2S corrosion in oil and gas fields is often associated with acidity and salinity of fluids. However, the role of salinity is usually ignored in corrosion studies and corrosion prediction models. As part of a major project to model uniform CO2/H2S corrosion of carbon steel oil and gas pipelines in high salinity environments, the research reported herein investigated uniform CO2 corrosion in high salinity acidic media. Experiments were carried out using a rotating disk electrode (RDE) in CO2-saturated aqueous solutions at 10°C and a constant pH of 3.0, whilst varying NaCl concentration from 1 wt.% to 20 wt.%. The RDE setup was used because mass transfer of species to the surface in this setup is well understood. A low temperature was chosen to better distinguish between charge transfer and mass transfer-controlled reactions underlying the corrosion process. Surface analysis indicated that the corrosion process was uniform, and no corrosion layer formed on the steel surface. Both linear polarization resistance (LPR) and potentiodynamic polarization (PD) techniques showed a general decrease in the uniform corrosion rate with increasing salt concentration. The analysis of the PD sweeps showed that salt concentration did not influence the mechanism of anodic and cathodic reactions and the decrease in the corrosion rate was due to deceleration in the rate of both anodic and cathodic reactions. Modeling results showed that salt concentration mostly affected the rate of mass transfer of H+ ion to the surface by changing H+ diffusion coefficient and H+ activity coefficient.

Many acidic geothermal wells with low-carbon steel casing materials benefit from the application of pH control chemicals such as NaOH. However, at high temperatures this can result in rapid scaling by anhydrite. In addition oxidation of iron in acid wells can lead to reductive deposition of heavy metals and in localized galvanic corrosion. Control of production fluid pH can require frequent adjustment of the NaOH addition. Corrosion inhibitors have been proposed as an alternative to pH adjustment in mildly acidic geothermal wells both for control of corrosion and scaling as well as for control of heavy metal deposition. In this study, a commercial corrosion inhibitor was used to quantify the level of corrosion mitigation of K55 casing material in simulated acidic geothermal electrolyte at different pH values and inhibitor concentrations. Results showed a decrease in corrosion rate as a function of increasing pH without inhibitor addition and a decrease in corrosion rate of over 90% with inhibitor addition at the lowest pH tested. The percentage decrease in corrosion rate was less at the higher pH values tested where the inhibitor free corrosion rates were lower and presumably controlled, in part, by iron sulfide/iron oxide formation.

A chromium–nickel austenitic stainless steel was plasma nitrided at 535, 585, 650, 735, and 785°C. After nitriding, the structure, thickness, and hardness of the surface layer, as well as the appearance and height of surface irregularities, were determined. The wear and corrosion resistance of the nitrided steels were tested and the percentage of magnetic phases present was determined. It has been established that nitriding markedly raises the wear resistance of the steel at pressures of 50, 200, and 400 MPa. The corrosion resistance of the steel in 0.05 M Na2SO4 at pH 3 decreases as a result of nitriding. Nitriding leads to the appearance of a multi phase structure in the surface layer, the proportion of the ferromagnetic a and γ’ phases being dependant on nitriding temperature. After nitriding at 785°C the proportion of these phases is minimal. At the same time, the steel has a high hardness and wear resistance and is susceptible to passivation.