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Coatings based on a graphene oxide–boron nitride/epoxy (GO–BN/EP) system were fabricated and applied for corrosion protection of metal substrates. GO–BN hybrid sheet synthesized by using a modified Hummers’ method had a higher lipophilicity than GO and BN. Then, GO–BN hybrid was incorporated into an epoxy coating to investigate the compactness and the corrosion protection ability of GO–BN hybrid/epoxy coating for metal substrates. The results show that GO–BN hybrid presents a desirable dispersibility in epoxy coating, exhibiting an outstanding barrier property for corrosive ions in a 3.5 wt% NaCl solution among the four systems under investigation. The present study set forth an innovative method to synthesize GO–BN hybrid in the field of corrosion protection.

This article reports the microstructure evolution in TP347HFG austenitic steel during the aging process. The experiments were carried out at 700°C with different aging time from 500 to 3,650 h. The metallographic results show that the coherent twin and incoherent twin are existed in the original TP347HFG grains, while they gradually vanished with the increase of the aging time. After aging for 500 h, a lot of fine, dispersed particles precipitated from the matrix, but they disappeared after aging for 1,500 h. When the aging time extend to 3,650 h, the precipitates appeared apparently coarse in TP347HFG steel, which include the M23C6 and σ phase; besides, the micro-hardness of TP347HFG also changes during the aging, which was closely related to the effect of dispersion strengthening and solution strengthening. The results of the nonlinear ultrasonic measurement reveal that the β′ of TP347HFG steel was also changed with the aging time. It first increased at 0–500 h, then reduced later, and increased finally at 1,500–3,650 h. The variation of β′ in TP347HFG was influenced by a combined effect of the twin microstructure and the precipitate phase, which indicate that the nonlinear ultrasonic technique can be utilized to characterize the microstructure evolution in TP347HFG.

A pyrochemical conversion of U 3 O 8 into metallic uranium by chemical and electrochemical reactions have been studied. Triuranium octaoxide was chlorinated by carbon tetrachloride gas in a stream of argon at different temperatures. The optimal conditions of the solid phase transformation were found, the conversion rate of U 3 O 8 is up to 99.30%. The mechanism of U 4+ ions reduction into metal uranium by the transient electrochemical technique in the fused 3LiCl-2KCl eutectic was studied. The results revealed that the U 4+ ions reduction to metallic uranium on inert electrode is a two-step reaction, which includes single electron exchange and three electrons exchange. The first step of reaction is reversible and it is controlled by the rate of the mass transfer in the scanning region 0.002–0.2 V/s, while the second step of reaction is irreversible. The diffusion coefficients of U 4+ and U 3+ ions were determined by the cyclic voltammetry. The galvanostatic electrolysis of the LiCl-KCl-UCl 4 melt led to the formation of metallic uranium on an inert solid plate and the formation of intermetallic compounds of different composition on the active liquid gallium cathode. It is concluded that U 4+ ions is easily reduced to metallic uranium in a short period of time during the galvanostatic electrolysis in molten salts.

PurposeThis paper aims to prepare a residual rust epoxy coating by adding different quantities of phytic acid (PA) on the surface of the rusty steel and investigate the corrosion protection of PA and its action mechanisms.Design/methodology/approachA residual rust epoxy coating by adding different quantities of PA was prepared on the surface of the rusty steel. The influence of PA on the corrosion resistance of epoxy-coated rusty steel was investigated by means of electrochemical impedance spectroscopy and adhesion testing.FindingsResults indicated that PA can substantially improve the corrosion resistance of epoxy-coated rusty steel. This improvement is due to the reaction of PA with residual rust and generation of new compounds with protection properties and increased adhesive strength effects on the coating/metal interface. The coating showed better protection performance when 2 per cent PA was added.Originality/valueConsidering the structure of the active groups, PA has strong chelating capability with many metal ions and can form stable complex compounds on the surface of a metal substrate, thereby improving corrosion resistance. In recent years, PA has been reported to be useful in the conversion of coatings or as green corrosion inhibitor. To the best of the authors’ knowledge, few studies have reported the use of PA as a rust converter or residual rust coating. The present work aims to improve the corrosion resistance of residual rust epoxy coating by adding PA.

The solar radiation is essential for multiple purposes in a wide set of human activities. Frequently direct measures can be rarely achieved via weather stations so that predictive approaches become of interest. In this paper, support vector regression (SVR) is employed to predict the daily horizontal direct solar radiation (DHDSR) considering Air Quality Index (AQI). Data from 6 locations during the period of 3 years compose the training and testing sets. For each location, 9 input parameters are considered, including the daily values for the most frequently adopted climatology parameters and air quality index (AQI). The polynomial and radial basis functions (RBF) are selected as the SVR kernel function to estimate the solar radiation. The statistical indicator of root mean square error (RMSE) ranges between 0.000363 MJ/m2 and 0.191051 MJ/m2, showing good performances of all the SVR models, while polynomial basis function based SVR is preferred for most cities due to its greater accuracy and less time consumption. Furthermore, Pearson Correlation is performed to identify the most relevant input for DHDSR prediction, which shows that sunshine duration, average relative humidity and maximum temperature are the most influential factors. The results indicate that the SVR method would be a good solution for estimation of daily horizontal direct solar radiation in China. This study provide an access to combine big data with solar radiation estimation with specific machine learning method.

A numerical simulation was conducted to study the heat transfer characteristics of R410A during flow boiling at low vapor quality in a horizontal tube. The thermal phase change model in Fluent was used to describe the flow boiling phenomenon and validated by the experimental data from the existing literature. The effects of mass flux and heat flux on the flow boiling heat transfer were clarified. The results showed that the heat transfer coefficient increased with the increase of mass flux while decreased with the increase of vapor quality due to the interaction of nucleate boiling and fluid convection. However, the effect of heat flux was slight on the flow boiling heat transfer coefficient indicating that the flow boiling was governed mainly by the fluid convection. The simulation results were compared with the predictive values of four well-known heat transfer correlations. The Kandlikar and Jung’s correlations underpredicted the heat transfer coefficient. The Sun’s correlation showed the best agreement with a mean absolute deviation mostly less than ±15% for heat transfer. This study makes up the gap of numerical simulation on the flow boiling of R410A and these results would be useful for the understanding of flow boiling mechanism of R410A and the design and optimization of heat exchanger and the substitution of refrigerants.

Seawater desalination is an energy-intensive process and many efforts have been made to reduce energy-consumption of desalination process. In this study, a new energy analysis model of seawater desalination based on thermodynamics is proposed. The minimum energy consumption of ideal desalination process is calculated out by subtracting the Gibbs free energy of seawater form the Gibbs free energy of freshwater. The results show that the minimum energy consumption for the ideal desalination process decreases with the increase of the salinity of freshwater, and increases with increase of the salinity of seawater and operation temperature. Compared the minimum energy consumption with the average energy consumption of plans in industry, there are much irreversible loss in the actual desalination process. For a given feed water quality and a given freshwater quality standard, the efforts should be made to invent new desalination technologies which can operate under low temperature condition.

The parabolic trough collector (PTC) is one of the most mature technologies to harvest solar energy for heat applications. However, the non-uniform heat flux distribution on the outer surface of absorber tube can lead to a high local temperature and a large temperature gradient on the tube wall, thus resulting into many issues, such as the degradation of the selective coating, the vacuum loss, the deformation of the absorber tube, and even the breakage of the glass envelope. These issues pose great challenges for the safety and high-efficiency operation of PTC systems. The corresponding effective solution is to increase the uniformity of the heat flux distribution on the absorber tube. Based on this purpose, how to quantify the uniformity of heat flux distribution is of great significance for the design of the parabolic trough collector. In this work, the existing uniformity indexes in engineering are summarized and compared. It is found that there are three problems in the related studies: (1) Some indexes are unbounded, which makes it difficult to compare uniformity of different distribution types; (2) some indexes are dimensioned, and its difficult to compare uniformity of different physical quantities distribution; (3) for most of the existing indexes, only the value of physical quantity is considered, while the spatial distribution characteristic of physical quantity is ignored. This phenomenon makes the description of uniformity incomprehensive. In view of this, a new uniformity index is proposed to consider both the value and spatial position of physical quantity by decoupling uniformity index into uniformity index of value and uniformity index of spatial position. The uniformity index of value is to quantify the dispersion degree of a set of data values from the average, and the uniformity index of spatial position is to quantify the amount of dispersion of data values in different spatial zones. The effectiveness of the proposed uniformity index is verified by evaluating the uniformity of three different distributions. Compared with existing uniformity indexes, the proposed index has a better ability to distinguish the uniformity of the distribution. Thereafter, the proposed uniformity index is employed to evaluate the uniformity of heat flux distribution in four typical types of PTC. The obtained results show that the proposed uniformity index can quickly and accurately evaluate the uniformity of heat flux distributions in PTC. Furthermore, due to the characteristics of strict boundedness and dimensionless, the proposed index can be easily applied as the guidance of PTC design and optimization.

Mixtures have been widely researched for organic Rankine cycle (ORC) application in various heat sources. In this contribution, the calculation errors of cycle performance are analyzed by investigating the property uncertainty of mixtures, based on the Helmholtz equation with three groups of binary interaction parameters (BIPs), namely newly fitted BIPs, estimated BIPs and BIPs = 1. Nine mixtures are selected for the ORC and six cycle parameters are determined under different molar fractions of mixtures and operating temperatures. When the results of fitted BIPs are considered as the basis of comparison, the relative errors of estimated BIPs and BIPs = 1 vary greatly with the molar fraction of mixture, but change little with the cycle temperature. Deviations of pumping work are always the largest among the considered parameters. For HFC/HFC mixtures, cycle parameters except pumping work have average absolute relative deviations (AARDs) less than 5%. However, for HFC/HC and HFO/HC mixtures, BIPs = 1 has an AARD of pumping work larger than 20%. The AARD of pumping work for the estimated BIPs is around 10%. In the future performance evaluation of alternative mixture with few or no experimental data, the above analysis is helpful for choosing appropriate BIPs and estimating the errors of cycle parameters.

The application of T-junction has already been extended from the petroleum engineering to the emerging advanced thermodynamic cycles. How a T-junction, as a separator in an emerging thermodynamic cycle, affects the cycle efficiency is discussed in this paper. Firstly, based on the Eulerian method, parametric studies on the local pressure drop coefficients are conducted and two new local pressure drop (LPD) coefficients are predicted in this paper. Then, the effects of pressure drop on a composition adjustable organic Rankine cycle efficiency is analyzed. In the process, a composition adjustable organic Rankine cycle with zeotropic mixtures R245fa/R123 is chosen to calculate the effects of pressure drop on thermodynamic cycle efficiency. The quality of the outlet of the evaporator is assumed as 0.7, and the composition ratio as 0.6/0.4. The results show that the pressure variation of T-junction affects the adjustable organic Rankine cycle efficiency, and reasonable phase separation ratio can improve the thermodynamic cycle efficiency. The pressure drop could cause composition diffusion. In addition, two new local pressure drop coefficients are obtained. And the results demonstrate that K12J declines slowly with the increases of density ratio (ρ2/ρ1) and decreases with the increases of mass fraction of taken off (F). K13J shows an obvious trend with diameter ratio (d3/d1) and F. This work could push the research of T-junction as a separator in the adjustable organic Rankine cycle.

Purpose This paper aim to investigate the influence of PA on the corrosion behavior of carbon steel with blast cleaned or pre-rusted treatments, and interpret the inhibition mechanism of PA on the steel with different surface treatments. Design/methodology/approach The influence of PA on the corrosion behavior of blast cleaned or rusty steel was investigated by means of electrochemical impedance spectroscopy (EIS). The EIS data were analyzed using the @ZsimpWin commercial software. The morphology and component of steel after immersion were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transformation infrared (FTIR) and X-ray diffractometer (XRD). Findings EIS analysis results indicated that PA had good corrosion inhibition for blast cleaned or rusty steel. SEM, EDS, FTIR and XRD further indicated that PA had two main corrosion inhibition processes for the corrosion inhibition of blast cleaned or rusty steel: corrosion dissolution and formation of protective barrier layers. Originality/value Most published works focus the attention only toward the effect of corrosion inhibitor for the clean metal surfaces. However, the surface condition of metal sometimes is unsatisfactory in the practical application of corrosion inhibitor, such as existing residual rust. Some studies also have shown that several corrosion inhibitors could be applied on partially rusted substrates. These inhibitors mainly include tannins and phosphoric acid, but not PA. Therefore, the authors investigated the influence of PA on the corrosion behavior of carbon steel with blast cleaned or pre-rusted treatments in this paper.

Graphene oxide–poly(urea–formaldehyde) (GUF) composites were prepared by anchoring a prepolymer of urea–formaldehyde resin onto graphene oxide (GO) sheets through in–situ polycondensation. Five GUF composites with 2.6, 4.3, 8.6, 20.8, and 34.6 wt.% GO sheets were synthesized and added into epoxy resin by ball milling. Results of sedimentation test, transmission electron microscopy, and cross–sectional microstructural analysis showed that GUF/EP coatings with 8.6 wt.% GO sheets were compatible with the polymer matrix. Electrochemical impedance spectra further revealed the optimal corrosion protection of GUF composites with 8.6 wt.% GO sheets.

Submicron-sheet zinc phosphate (SZP) was synthesised by sol–gel method. Anticorrosion behaviour of epoxy coating with SZP was investigated by electrochemical impedance spectroscopy, gravimetric test, adhesion test and scanning electron microscopy. Results showed that the submicron-sheet structure of SZP pigment can reduce defects in the coating, improve consistency of pigment/resin interface and lengthen diffusion pathways. SZP pigments in coating had more contact area with permeating water, ensuring PO 4 3− quickly attained the specific density to inhibit corrosion on the steel surface. Thus, SZP pigment can enhance the barrier properties of coatings and effectively inhibit the corrosion reactions at coating/metal interface.

Creep damage assessment in HR3C steel was investigated by using the misorientation parameters in this study. The GROD, GOS, and GOS/D values in HR3C presented a monotonic increase tendency during creep. The largest rise of the misorientation parameter is GROD, which increased 322.80% after crept for 1300 h at 650℃/220 MPa. Besides, further analysis showed that the GROD value was far larger at those places that are close to the grain boundaries. Thus, the GROD can be used to characterize the intergranular damage in HR3C so as to prevent its catastrophic intergranular failure.

A numerical model is applied to simulate local pressure drop of R134a in a horizontal dividing T-junction, and the effects of mass flux in branch, liquid density and liquid viscosity on local pressure drop are calculated and a different viewpoint on reasons of the pressure changes in T-junction intersection area is preliminarily proposed. Eulerian model is applied in the numerical model. The simulation results are in a good agreement with experiment data. When the liquid density and viscosity increase, the local pressure drop from inlet to branch increases and the pressure rise from inlet to outlet increases, and the viscosity has little effect on local pressure drop which can be attributed to that the effects of viscosity on local pressure drop in horizontal T-junction can be negligible compared to effects of collision.

Grinding time and grinding rotation speed of iron oxide surface modification using high-temperature ball milling method were studied on the basis of the optimal grinding temperature. The modification effect of iron oxide improved with the grinding time extended from 1 h to 5 h and with the grinding rotation speed increased from 300 r/min to 516 r/min. The content of iron oxide to the corrosion performance of epoxy coatings was also investigated. The results show that the modified iron oxide can improve the corrosion performance of epoxy coating, and the optimal content of modified iron oxide in epoxy coating is about 10 wt.%.

Currently, the significant energy penalty and performance limitation of energy consumption are the main technical barriers to the large-scale applications of CO2 capture. Carbon pump, which realizes an enrichment of CO2 from carbon source to carbon sink, is applied in a modeling for energy-efficiency analysis of CO2 capture technologies. In this study, two adsorption technologies, including vacuum-pressure swing adsorption (VPSA) and pressure-temperature swing adsorption (PTSA), are compared in terms of the minimum separation work and the second-law efficiency. Based on carbon pump, two adsorption cycles can be presented through the process expression in the adsorption isotherm diagram, which is an easy pathway to show CO2 adsorbed amounts for each step. The influence of process parameters for VPSA and PTSA were studied as well. Results show that the maximum values of the second-law efficiency are 24.30% and 19.09%, respectively for VPSA and PTSA with the change of CO2 concentration from 5% to 25%. However, the second-law efficiency for VPSA and PTSA decreases with the increase of the other three factors, including desorption temperature, pressure of the feed and percent of unused bed. Parameters of component in cycle should also receive more attention for energy-efficiency analysis.

The emeraldine base and salt (hydrofluoric acid and camphorsulfonic acid doped) forms of polyaniline (PANI) were synthesized and added to be epoxy coating. The corrosion protection of different PANI coatings was studied by EIS. Results indicated that different PANI coatings could offer the corrosion resistance of mild steel. However, the camphorsulfonic acid-doped PANI coating had the best performance in corrosion protection among the four systems under investigation. The corrosion product layer was analyzed by SEM and XPS, indicating that PANI changed the morphology and component of the corrosion product layer. Moreover, the protective mechanism imparted by PANI was discussed.

Four kinds of graphite derivatives in different exfoliation degrees were synthesized via modified Hummers’ method by controlling the mass ration of graphite and KMnO4 . The modified graphite derivatives (GUF) were synthesized through chemical modification with the prepolymer of urea–formaldehyde. Results of Raman spectroscopy (Raman) and Scanning electron microscopy (SEM) revealed that the layer exfoliation was affected by oxidation degree during the preparation of graphene oxide (GO). The highly exfoliated GO was fully modified by UF resin and presented excellent compatibility with epoxy resin. The data of electrochemical impedance spectra (EIS) verified the optimal corrosion resistance of GUF/EP composite coating with the highly exfoliated GO sheets. The data of localized electrochemical impedance spectroscopy (LEIS) demonstrated that the highly exfoliated modified GO exhibited slight galvanic corrosion in the defective coatings.

The study investigates contaminant removal and oil-water separation efficiencies of magnetic Fe3O4 nanoparticle (MNP)-coated fluorinated carbon fabric (CF) membrane. A co-precipitation method was adopted to synthesize spherical MNPs with an average size of 20 nm. The as-prepared MNPs were uniformly dispersed and coated over the CF membrane, forming a two-tier roughened surface. Herein methylene blue (MB) and Cu2+ ion serve as adsorbate for evaluating the removal performance of the CF membrane. The MNP-coated CF membrane exhibits superior adsorption ability toward cationic MB molecules and Cu2+ ions in liquid phase, attributed to a synergistic effect that combines with porous CFs and Fe3O4 magnetite. The capacities for adsorption of MB and Cu2+ onto the MNPs are ca. 30.1 and 62.5 mg/g, respectively. The hydrophobicity and oleophobicity of the CF membrane were effectively improved by the MNP-coated fluorination approach. The improved repellencies mainly originate from the fact that the decoration of Fe3O4 magnetite and the surface fluorination, covering the CF surface, create a two-tier framework against the wetting of liquid droplets. The CF membrane shows fast removal rate of oil drops and excellent efficiency of oil-water separation (>95%). On the basis of the experimental results, the functional CF membrane offers a commercial feasibility for a variety of applications such as environmental protection and wastewater treatment.

Purpose The purpose of this paper was to research the influence of polyaniline/montmorillonite (PANI/OMMT) composite powder content on the corrosion protection of epoxy (EP) coating. Design/methodology/approach The polyaniline/montmorillonite/epoxy (PANI/OMMT/EP) coatings containing different contents of PANI/OMMT composite powder were prepared on steel. The corrosion protection performances of PANI/OMMT/EP coatings in 3.5 per cent NaCl solutions were investigated by electrochemical impedance spectroscopy. The barrier property of coatings was examined using water absorption analysis. The structure and crosslink density of coatings were examined using scanning electron microscopy and differential scanning calorimetry, respectively. Findings The PANI/OMMT composite powder could enhance the barrier properties of the EP coating and reduce the corrosion rate of the steel beneath the coating. The coating showed the best corrosion protection performance when 3 per cent PANI/OMMT powder was added to the coating. Originality/value The research clarified the influence of PANI/OMMT content on the corrosion protection of coating from two aspects: one is the barrier performance of the coating; the other is the corrosion inhibitors for metal substrate.

Nanocrystalline nickel coatings with grain size of 50 nm were annealed in vacuum at 200 °C and 400 °C for 10 min. Their microstructures were investigated by transmission electron microscopy (TEM). And their corrosion behaviors were studied by means of polarization and electrochemical impedance spectroscopy (EIS). The results showed that their grain size grew up to about 60 nm (200 °C) and 500 nm (400 °C), respectively. The specimen annealed at 200 °C possessed higher density of twins in compared with the counterparts of as-deposited and annealed at 400 °C. The normal grain size effect on the corrosion behavior was not observed. However, it was found that the corrosion resistance of the coating linearly changed with the density of twins.

The electrode reactions of the Ce3+/Ce couple in molten LiCl–KCl eutectic in the temperature range 723–823 K on solid Mo electrodes were investigated by electrochemical techniques. The mechanism of deposition of metallic cerium has been established. It was found that the cathode reaction is irreversible and proceeds in one stage. The apparent standard Gibbs energy of CeCl3 formation from the elements was calculated. The values of enthalpy and entropy were equal: ΔH* = − 1000.2 kJ/mol, ΔS* = 166.0 J/mol·K. The conditions of high-purity cerium production have been studied. The chemical structure of cathode deposits as well as the surfaces of the crucible were investigated by XRD, ICP and SEM-EDS methods. It was established that the best results for purification of the cathode product from impurities were achieved in the range 40–60 mA/cm2 using a two-stage electrolysis. The amounts of the main impurities in the final product were 0.005 wt% Al, 0.0021 wt% Fe, and 0.003 wt% Si. The total purity of metallic cerium after cleaning was increased up to 99.971 wt% if a vitreous carbon crucible was used.

The anti-corrosion properties of the defective zinc phosphate/epoxy coatings under cathodic protection (CP) in a 3.5% NaCl solution were evaluated by localized electrochemical impedance spectroscopy (LEIS), scanning electrochemical microscopy and X-ray diffraction. The results revealed that the application of CP inhibited the formation of the phosphate film, compared with exposure at open circuit potential (OCP). Moreover, a CP/OCP cycle was beneficial to form a phosphate film on the defective coatings, particularly under a −0.65 V/OCP cycle. The mechanism of zinc phosphate modifying the corrosion process of the defective coatings under different cathodic potentials was also considered.

Nickel coatings with different microstructures were synthesized by pulse jet electrodeposition technique. Their morphology and microstructure were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The corrosion property of the coatings was studied by using polarization, electrochemical impedance spectroscopy (EIS), potential of zero free charge (PZFC) measurements and Mott–Schottky ( M–S ) relationship. The results showed that the coating with grain size of 50 nm possessed higher corrosion resistance than that with grain size of 10 nm. This abnormal behavior may be related to the existence of nanoscale twins in the coatings and the lower concentration of acceptor in the passive films.

Response surface methodology (RSM) is introduced into corrosion research as a tool to assess the effects of environmental factors and their interactions on corrosion behavior and establish a model for corrosion prediction in complex coupled environment (CCE). In this study, a typical CCE, that is, the corrosion environment of pipelines in gas field is taken as an example. The effects of environmental factors such as chloride concentration, pH value and pressure as well as their interactions on critical pitting temperature (CPT) were evaluated, and a quadratic polynomial model was developed for corrosion prediction by RSM. The results showed that the model was excellent in corrosion prediction with R 2 = 0.9949. CPT was mostly affected by single environmental factor rather than interaction, and among the whole factors, chloride concentration was the most influential factor of CPT.

Defective epoxy varnish and hydrofluoric acid-doped polyaniline/epoxy (PANI-HF/EP) coatings were coated on the surface of an AZ91D magnesium alloy. The corrosion protection of the defective coatings was evaluated in 0.05 M NaCl by localized electrochemical impedance spectroscopy. Then, the surface of AZ91D magnesium alloy beneath the coating was analyzed by scanning electron microscopyand energy dispersive X-ray spectroscopy. The results indicated that the defective epoxy varnish coating could not protect the magnesium alloy because it only served as an electrolyte barrier. By contrast, the PANI-HF/EP coating served not only as an electrolyte barrier, but also facilitated the formation of a protective layer by redox processes. Therefore, the defective PANI-HF/EP coating could protect magnesium alloy from corrosion.

The effect of pitting nucleation on critical pitting temperature (CPT) of 316L stainless steel is investigated by electrochemical measurements, morphology observation and XPS analysis. CPT increases dramatically after being passivated by nitric acid, which is mainly attributed to inclusions dissolution and Cr 2 O 3 enrichment in passive film. However, the thickness of passive film is less influential. Pitting nucleation is suppressed through passivation, which leads to the increase of pitting nucleation temperature. Consequently, critical current density ( i crit ) shifts to higher temperatures, indicating the enhancement of CPT. In other words, CPT is influenced by both pitting growth chemistry and pitting nucleation.