Study on Catalytic Oxidation, Flocculation and Sedimentation of Acidizing and Fracturing Wastewater

The acidizing and fracturing waste fluid in a wellsite in northern Shaanxi was treated by catalytic oxidation and flocculation precipitation. It investigated the effect of different coagulants and their dosage and the wastewater pH on coagulation precipitation. As for chemical oxidation experiment, it investigated the effect of oxidant dosage and reaction time on its treatment effect. The results showed that when 30% hydrogen peroxide (volume percentage) was added at the dosage of 0.3% and oxidized for 50 min, the pH was adjusted to 7.5 and 350 mg/L polyaluminum chloride (PAC) and 4 mg/L polyacrylamide were added (PAM); after processing the waste liquid, total iron, chemical oxygen demand (COD), chromaticity, and average corrosion rate were reduced from 252.75 mg/L, 3427.50 mg/L, 624.15°, and 0.1226 mm/a to 0.12 mg/L, 275.18 mg/L, 125° and 0.0217 mm/a, respectively; effective removal of iron and color, reduced COD, and controlled corrosion was achieved.

Design and characterization of novel zirconium-based amorphous alloys containing scandium for biomedical application

In this work, (Zr55Cu30Al10Ni5)100−xScx (x = 0, 0.5, 1.0, and 1.5) amorphous alloys were fabricated through steel die casting. The effects of scandium on the properties of zirconium-based amorphous alloys have been studied. The results show that the glass-forming ability of amorphous alloys increases at first and then decreases with the increase of Sc content. The highest glass-forming ability is obtained when the atomic fraction of Sc is 0.5%, which enables the production of 2-mm-thick amorphous alloy ingots. Meanwhile, the thermal stability and mechanical properties of the alloy are optimised with the atomic fraction of Sc of 1.0%. In addition, by adding an appropriate amount of Sc, the corrosion resistance of Zr–Cu–Al–Ni alloys is enhanced, particularly in the acid solution. The lowest average corrosion rate for samples in acid solution is obtained with the alloy containing atomic fraction of Sc of 1.0%. Therefore, results of this study indicate that the Zr-based amorphous alloy containing scandium has the potential for manufacturing fracture internal fixation or surgical devices.

RELATIONSHIP BETWEEN SOIL ENGINEERING PROPERTIES AND CORROSION RATE IN ANDESITIC VOLCANIC SOILS, WEST LAMPUNG, SUMATRA, INDONESIA

Soil is the most diverse environment that can cause metal corrosion. Many researchers claim that soil is a corrosive environment that has complexity compared to other environments. With a background knowledge of soil engineering properties in a specific area and their effects on the metal corrosion process then corrosion problems can be prevented. This paper presents the relationship between andesitic volcanic soil engineering properties with an average corrosion rate based on geotechnical and statistical methods. In this paper, we propose a new average corrosion rate per year on that soil. The study area took place on the Sekincau-Way Tenong Transect Road, West Lampung, Sumatra, Indonesia. This area was composed of silty clay to clayey silt soils which weathering products from andesitic-basaltic volcanic breccia. This soil can store water that is moderate to high and has high plastic properties. Based on the statistical approach, it can be concluded that the corrosion rate in andesitic volcanic soils is 1.132 mm/yr. Soil engineering properties (water content, index plasticity, and clay content) simultaneously affect the average corrosion rate. The effective contribution of each independent variable (soil engineering properties) to the corrosion rate is a plasticity index of 39.5%, the water content of 24.79%, and clay content of 26.04%. Index plasticity and water content were found to raise the average corrosion rate at the soil samples, while clay content was on the side that lowered the average corrosion rate.

Corrosion Resistance Analysis of ST37 Carbon Steel Material Using Phosphate Conversion Coating in Various Immersion Durations

Conversion coating in metal material was a method to control the corrosion. It applied in parts of car, aircraft, factory installation, and other appliances. There were three types of conversion coating: phosphate conversion coating, chromate conversion coating, and oxalate conversion coating. There were several aspects to consider in controlling the corrosion fully. This research used phosphate because phosphate conversion coating had a low corrosion rate, affordable production cost, and environmentally friendly. This research aimed to find out the corrosion resistance of ST37 carbon steel using phosphate conversion coating in various immersion durations. Therefore, the result was a breakthrough in using phosphate conversion coating for the industries. This research used the weight loss method to calculate the corrosion rate and macro photos to obtain the corrosion form during the test. This research used ST37 carbon steel with 100 mm x 30 mm x 10 mm as the specimen and phosphate with various coating durations (10, 20, and 30 minutes). Each variation had three specimens, so this research had nine specimens in total. This research calculated the daily corrosion rate for seven days using 5% NaCl as the corrosion solution. The average corrosion rate in specimens with 10 minutes duration was 1.9599 mpy, specimens with 20 minutes immersion was 1.7647 mpy, whereas specimens with 30 minutes duration were 1.3287 mpy. Thus, the longer immersion duration created a smaller corrosion rate. Also, the corrosion formed during the test was pitting and uniform corrosion.

Research on Anticorrosive Effects of Larch Bark Extract with Addition of Collagen

The results of the study of the anticorrosive protective effects of the larch bark extract with addition of collagen have been given in this article. It was found that the best way of water extraction of tannins from larch bark is a temperature of 60 ° C during 1 hour, since at high temperatures, partial destruction of tannins occurs, and with an increase in the extraction time of more than an hour, the process of adsorption of these substances by the bark takes place. The corrosion rate was determined by the intensity of the blue colour of the complex compound of iron (II) cations - the truncul blue Fe3[Fe (CN)6]2 on a photocolorimeter with a yellow light filter at a wavelength of 590 nm. The average corrosion rate was calculated by the concentration of the resulting Fe2+ cations (within 1 minute). Based on the average corrosion rates, the protective effect of the extract (Z) and the drag coefficient (γ) were determined. It has been identified that the protective effect of the larch bark extract is equal to 37.5%, while addition of collagen leads to 2.3 time increase of protective effects of the extract. This can be explained by the fact that, with collagen additive, good adhesion of tannins to the surface of iron occurs resulting from formation of complex compounds, and a protective collagen film is formed, preventing an access of oxidizing agents to the metal surface.

Research and test on anti-corrosion and anti-scaling technology of downhole injection tools of Dagang Southern Oil Field

Every year, water well inspection operations accounted for 27.3% of the total water well operations due to corrosion and scaling of downhole injection tools in the Dagang Southern Oil Field, which seriously affects the validity period of the injection string and the effect of the injection, greatly increasing the production cost. Therefore, through the research and experiment of anti-corrosion and anti-scaling technologies such as 00Cr25Ni7Mo3N dual-phase steel material, TiN coating, Ni-W-P coating and Ni-W-P-nSiO2 composite coating, a new type of anti-corrosion and anti-scaling technology for downhole injectiong tools has been developed. The field test results show that under the premise of ensuring the mechanical performance of the tools, the average corrosion rate of the supporting tools using the new anti-corrosion and anti-scaling technology is 0.0048mm/a, which is far lower than the industry standard 0.076mm/a. The successful test of this technology is of great significance to increase the effective period of the southern oilfield split injection and reduce production costs.

Effects of Minor Sr Addition on Biocorrosion and Stress Corrosion Cracking of As-Cast Mg-4Zn Alloys

Microstructure, biocorrosion, and stress corrosion cracking (SCC) behavior of as-cast Mg-4Zn-xSr alloys (x ≤ 0.4, in mass%) are studied by scanning electron microscopy, immersion testing, slow strain rate tensile testing, etc. A minor Sr addition (≤0.2%) in Mg-4Zn alloy can reduce the average corrosion rate and the corrosion current density in Hank’s solution, resulting from grain refinement, dispersion of the smaller secondary phase particles, and the more-protective corrosion product film. Thus, a minor Sr addition (≤0.2%) can improve both strength and plasticity of the Mg-4Zn alloy without increasing the SCC susceptibility, and the Mg-4Zn-0.1Sr alloy exhibits the best comprehensive properties.

Changes in Corrosion of X70 Steel in Water-Saturated Supercritical CO2 System Caused by Impurity

During the process of Carbon Capture and Storage, some impurity may be found in the supercritical CO2fluid. The changes in corrosion of X70 Steel in water-saturated supercritical CO2system caused by impurity has been studied by the simulation experiment. The average corrosion rate was got from weight loss measurement. The morphologies and compositions of corrosion products were analyzed by SEM, EDS and XRD. It was observed that the existence of separate impurity would aggravate the corrosion of X70 steel in the water-saturated supercritical CO2system. The average corrosion rate was the highest when NO2or SO2was included, followed by H2S, and the average corrosion rate was the smallest when O2was contained. Among them, X70 steel suffered local corrosion when NO2was contained. The corrosion scale was monolayer structure of FeCO3under the supercritical CO2-H2O system. After the addition of O2, Fe2O3appeared in the corrosion scale, indicating that the oxygen corrosion process occurred. While with the addition of H2S, corrosion scales were double layers. FeS was mainly present in the outer layer. The corrosion process was controlled by CO2and H2S. The corrosion products were mostly FeSO3·xH2O and a spot of FeCO3when SO2was contained. SO2mainly governed the corrosion process. Besides, corrosion product was Fe2O3without FeCO3in the supercritical CO2-H2O-NO2system, NO2completely controlled the corrosion process.

Application of vapor phase corrosion inhibitors for contaminated environments

Availability and accessibility to clean water for industrial applications such as hydrotesting and hydrostatic testing of pipelines, vessels, and plumbing distribution systems has been a challenging task especially when the job sites are in remote locations. When contaminated water is used in these tests, corrosion of the metallic components of the systems, during and after testing become a major concern. Vapor-phase corrosion inhibitors (VCI), can be added to water in small concentrations to prevent corrosion during testing, during wet storage and after testing. These inhibitors are to prevent corrosion of metallic components in three phases, within the solution, at the water line, and above the water line. Three commercially available corrosion inhibitors were evaluated in this investigation. Laboratory studies are presented in this paper, showed the effectiveness of VCI products in both fresh and salt water applications. Average corrosion rate dropped from ~10 mpy for salt solution to less than 1-1.6 mpy when various inhibitors was added. The effectiveness of these inhibitors is remarkable in the fresh water (less than 0.4 mpy). Exposure of the steel samples to these inhibitors did not show any loss in mechanical properties. Both strength and ductility of the low carbon steel samples was maintained.

Utilization of cigarette clove, tobacco leaf, and coffee as iron inhibitor

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.