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.

Comprehensive analysis and assessment of prospective gold-ore zones using modern geophysical methods

В статье рассматривается комплексный анализ геологической и геофизической информации по проводимым исследованиям с целью выделения перспективных участков для проведения дальнейших геологоразведочных работ. Цель работы. Провести комплексный анализ и оценку перспективных золоторудных зон с применением современных геофизических методов. Методы работы. Вертикальное электрическое зондирование методом вызванной поляризации, метод вызванной поляризации в модификации срединного градиента, геоэлектрические разрезы по профилям, аномалии поляризуемости поля электрических сопротивлений, метод ТЗ электротомографии. Результаты работы. Авторами в 2019 г. в северной части участка на площади 2,87 кв. км были выполнены работы СГ-ВП по сети 50×10м с MN – 10 м. и АВ – 2000 м. Измерения DU и φвппроводились на частоте 1.22 Гц измерителями МЭРИ – 24 и ЭИН – 209 (режим измерения частотный). Использовался генератор ГЭР – 5000 – 25 (мощность 5 кВт). По результатам измерений построены карты изолиний поляризуемости и кажущегося сопротивления. Следует отметить, что при определении сдвига фаз φвп в частотном режиме сигнал, используемый для измерения сдвига фаз при равных DU с импульсным режимом измерений в 30-100 раз выше. Это основное преимущество фазовых измерений над импульсными. Как видно из приведенного сравнения уменьшение длины приемной линии и шага наблюдений позволило увеличить детальность исследований СГ-ВП и выйти на уровень рудных тел, заданных в техническом задании. По результатам ТЗ электротомографии и ВЭЗ-ВП получены близкие результаты, хотя методически и теоретически ТЗ обладает в данных условиях большей детальностью и информативностью. По результатам геофизических работ построены карты изолиний и графиков ρк и φвп, выявлена их связь с рудовмещающими структурами и отдельными рудными телами. Всего выявлено 14 локальных аномалий поляризуемости связанных с золото-кварц-сульфидными и сульфидными рудными телами. Выявлены площадные аномалии повышенной поляризуемости и низких значений электрического сопротивления СГ-ВП вдоль Западной рудно-тектонической зоны. Они связаны с метасоматическими процессами в пределах Западной зоны сбросо-сдвигов. На площади работ отмечены слабоконтрастные аномалии магнитного поля в северо-западной части Северной зоны. Отмечено сильное влияние рельефа на характер магнитного поля, вследствие чего наблюдается корреляция хребтов с минимумами магнитного поля. The article discusses a comprehensive analysis of geological and geophysical information on ongoing research in order to identify promising areas for further exploration. Aim. Conduct a comprehensive analysis and assessment of promising gold ore zones using modern geophysical methods. Methods. Vertical electrical sounding by the induced polarization method, the induced polarization method in the modification of the median gradient, geoelectric sections along the profiles, anomalies of the polarizability of the electrical resistance field, TK method of electrotomography. Results. The authors in 2019 in the northern part of the site on an area of 2.87 sq. km SG-VP works were performed on a network of 50 × 10m with MN -10m. and AB - 2000 m. Measurements of DU and φvp were carried out at a frequency of 1.22 Hz with meters MARI - 24 and EIN - 209 (frequency measurement mode). Used generator GER - 5000 - 25 (power 5 kW). Based on the measurement results, maps of isolines of polarizability and apparent resistivity were constructed. It should be noted that when determining the phase shift φvp in the frequency mode, the signal used to measure the phase shift at equal DU with the pulse measurement mode is 30-100 times higher. This is the main advantage of phase measurements over pulsed ones. As can be seen from the above comparison, a decrease in the length of the receiving line and the step of observations made it possible to increase the detail of SG-VP studies and to reach the level of ore bodies specified in the terms of reference. Based on the results of the technical specification for electrotomography and VES-IP, similar results were obtained, although methodologically and theoretically, the technical specification has greater detail and information content under these conditions. Based on the results of geophysical work, maps of isolines and graphs of ρк and φвп were constructed, their relationship with ore-bearing structures and individual ore bodies was revealed. In total, 14 local anomalies of polarizability associated with gold-quartz-sulfide and sulfide ore bodies have been identified. Areal anomalies of increased polarizability and low values of electrical resistance of SG-VP were revealed along the Western ore-tectonic zone. They are associated with metasomatic processes within the Western fault-strike zone. Low-contrast magnetic field anomalies in the northwestern part of the Northern Zone were noted in the survey area. A strong influence of the relief on the nature of the magnetic field was noted, as a result of which a correlation of the ridges with the minima of the magnetic field is observed

The inhibitory properties of ion-modified zeolite for priming paint coatings

The anticorrosion environmentally friendly pigments based on synthetic zeolite for paint coatings were obtained by liquid-phase ion exchange method. Zeolite was modified with zinc, calcium and manganese ions. The corrosion resistance of 09G2C steel in 0.1% NaCl solution and in suspensions of modified zeolite was investigated by potentiodynamic polarization method. It was shown that the use of zeolite modified with cations of divalent metals contributes to the reduction of corrosion currents. It was found that the zeolite modified with zinc cations exhibits the most anticorrosion effect relative to 09G2C steel, as indicated by the values of corrosion currents (which are ~2 times smaller than in the non-inhibited solution) and the results of electrochemical impedance spectroscopy. The surface morphology of 09G2S steel after exposure to the inhibited media was determined by scanning electron microscopy. Protection mechanism of the modified zeolite was suggested.

Dual-Frequency Induction Polarization Electric Field Focusing Based on Intelligent Algorithm for Coal Mine Electric Exploration

As the most important and dangerous front-end production link, coal mining operations will inevitably face geological disasters such as water inrush, rock burst, collapse, and fire, posing a great threat to the life and safety of miners. Among the five major geological disasters (gas, dust, water, fire, roof) in coal mines, the threat of flooding is very serious and it is one of the main disasters in coal mines. The research and development of dual-frequency excitation technology and its application in coal mine exploration have realized the elimination of potential safety hazards, improved the work efficiency and safety factor of prospectors, and realized the automated operation of the exploration process. This article explores the electric field of the intelligent algorithm’s focused dual-frequency induced polarization method in coal mine electrical exploration, and summarizes some of the advantages of the intelligent algorithm’s focused dual-frequency induced polarization method in coal mine surveying on related materials, and then conducts related experiment, through the experiment of focusing on the dual-frequency IP method in the coal mine survey, obtained the result, in the abnormal point detection experiment, the change trend of the two curves is the same, the increase is more obvious at 1.3-1.5m, and at 1.5m When reaching the limit value, when it exceeds 1.5m, it starts to fall. It shows that when there is a water-bearing anomalous body directly in front of the tunneling section, the measurement results of the two survey lines are roughly the same. Compared with the no anomaly body, the apparent resistivity and the apparent amplitude frequency both change significantly, and reach the extreme in a certain direction. However, the actual anomalous body is located 1.0m directly in front of the tunneling section, which means that the actual position of the anomaly cannot be determined based on the apparent resistivity and the extreme point position of the apparent amplitude frequency.

Relationship Between Induced Polarization Relaxation Time and Hydraulic Characteristics of Water-Bearing Sand

Induced polarization method has become a popular method for evaluating formation permeability characteristics in recent years because of its sensitivity to water body and water-bearing pore structure. Especially, the induced polarization relaxation time can reflect the macroscopic characteristics of the pore structure of rock and soil. Therefore, in order to study the relationship between relaxation time and permeability, eight different sizes of quartz sand were used to simulate water-bearing sand layers under different working conditions, and the induced polarization experiment and Darcy seepage experiment were carried out on the same sand sample in this paper, respectively. The experimental results show that the relation time and the evolution of the permeability are closely correlated with the sizes of quartz sand. According to the experimental data, with the particle size of the quartz sand as the link, the power function equation is fitted to better describe the relationship between the permeability and the relation time. It is worth noting that the equations obtained are only empirical equations for quartz sand and are not suitable for general applications.

Water Extraction from Fully Polarized SAR Based on Combined Polarization and Texture Features

Given the limited features (for example, the backscattering coefficient threshold range) of single-channel Synthetic Aperture Radar (SAR) images, it is difficult to distinguish ground objects similar to the backscattering coefficients of water bodies. In this paper, two representative research areas are selected (Yancheng Coastal wetland and Shijiu Lake), and the fully polarized SAR data based on Gaofen-3 are used to extract water bodies using the method of polarization decomposition and gray level co-occurrence matrix. Firstly, the multi-dimensional features of ground objects are extracted, and then the redundancy processing of multi-dimensional features is carried out by the separability index, which effectively solves the misclassification of non-water bodies and water bodies and improves the accuracy of water body extraction. The comparison between the results of full-polarization extraction and single-polarization extraction shows that both full-polarization and single-polarization extraction can extract water information, but the extraction accuracy of the full-polarization method can reach 94.74% in the area with complex wetland features, which can effectively compensate for the lack of precision of the single-polarization method. Although multi-dimensional features can be extracted from fully polarimetric SAR data, data redundancy may exist. Therefore, using the Separability index (SI) to process multi-dimensional features can effectively solve the problem of feature redundancy and improve classification accuracy.

The Forward Modeling for Surface-borehole Observation Responses of Polarized Target

Surface-hole induced polarization method is a typical deep resource exploration technology, which plays an important role in the mineral survey. The traditional surface-hole induced polarization method is mainly to observe a single polarized secondary field. At present, the time spectrum observation of polarization fields is becoming more and more popular, which greatly enriches the interpretation technology of induced polarization data. In this work, the time spectrum induced polarization method is expounded, the decay polarization fields were numerical calculated and analyzed for the typical 2-dimensional geoelectric model. The results show that for a single polarized target, the time spectrum obtained from different azimuth observation responses are basically the same, which can effectively reflect the time-varying characteristics of the polarized fields. The observation responses of polarized target at different depths can still reflect the time spectrum of decay fields. The main change of the observed response of the polarized target closer to the borehole is the response amplitude. The conclusions and simulations of this study can provide working mode for relevant research and reference for similar work.

Chromate and Molybdate Inhibitors Effects on Corrosion Charateristic of API 5L Grade B in a Brine Water Solution Containing 8 % NaCl

Piping systems at gathering stations in the oil and gas industries often fail due to corrosion attacks from the brine water solution containing 8% NaCl that flows through the system. This solution is highly corrosive on the API 5L grade B steel pipes, thereby shortening its lifespan, with an increase in the frequency of pipe replacements. However, the corrosion resistance of API 5L grade B pipes can be improved by using chromate and molybdate inhibitors. Therefore, the objective of this research is to improve the corrosion resistance of the steel pipes using sodium chromate (Na2CrO4) and sodium molybdate (Na2MoO4) inhibitors with concentrations of 0.2, 0.4, 0.6, 0.8 and 1,0%. This research also aim to determine the optimum concentration of inhibitors to produce minimum corrosion rate, by testing the brine water solution containing 8% NaCl through the potentiodynamic polarization method. The results show that generally, the addition of sodium chromate and sodium molybdate inhibitors to the brine solution causes the steel pipes to be more resistant to corrosion. Furthermore, the sodium chromate inhibitor concentration of 0.6% produces the greatest corrosion potential of – 400 mV with the lowest rate of 0.38 mpy, while sodium molybdate concentration of 0.4% produces the highest corrosion potential of – 385 mV with the lowest rate of 0.34 mpy. The results of SEM observations at 0.4% sodium molybdate concentration showed that the corrosion inhibition/passivation effect of the inhibitor made the steel surface smoother, while the sodium chromate inhibitor at similar percentage failed to reach the optimal concentration to inhibit the corrosion process.