Multilayer architecture is an effective strategy for designing coatings with superior comprehensive properties. In this paper, CrAlN/CrSiN multilayer coatings were synthesized using a hybrid magnetron sputtering and arc ion plating process, aiming to integrate the high hardness of CrSiN with the excellent oxidation resistance of CrAlN. Microstructure and properties of the multilayer coatings were studied systematically, compared with CrAlN and CrSiN monolayer counterparts. All coatings exhibit a face-centered cubic structure. The multilayer coatings exhibit a finer grain size, higher hardness and elastic modulus, and significantly lower residual stress compared with monolayer coatings. The CrSiN and CrAlN/CrSiN coatings exhibit lower friction coefficients and wear rates than the CrAlN coating, due to their enhanced mechanical properties and formed self-lubricating silicon oxides. The multilayer coatings possess substantially extended tool life compared with the monolayer coatings. Although the multilayer coatings exhibit a slightly higher wear rate than the CrSiN monolayer, the high internal stress of the CrSiN coating promotes premature delamination under dynamic cutting loads, leading to catastrophic failure. Furthermore, reducing the modulation period enhances the mechanical, tribological, and cutting performance due to the increased interfaces that hinder dislocation motion and crack propagation. These findings offer valuable guidance for designing high-performance protective multilayer coatings.

TiB2 coatings are expected to have broad applications in wear-resistant fields owing to their high hardness, good wear resistance, and high thermal stability. However, these coatings are extremely brittle and prone to fracture during use. Existing research, both domestically and internationally, has introduced nitrogen into TiB2 coatings to form nc-TiN / a-BN nanocomposite structures to improve the coating toughness. However, it was found that even the introduction of a small amount of nitrogen leads to the formation of a significant amount of amorphous BN, resulting in a decrease in the coating hardness. To optimize the coating performance, this study uses high-power pulse magnetron sputtering, and the deposition temperature is varied to prepare the Ti-B-N coatings. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to analyze the microstructure and composition of the Ti-B-N coatings. A microhardness tester, scratch tester, and friction and wear testing machine are used to measure the hardness, film / substrate adhesion strength, and friction and wear properties of the Ti-B-N coatings. The effects of the deposition temperature on the structure, friction, and wear properties of the Ti-B-N coatings, as well as their wear mechanisms, are investigated. The results indicate that, as the deposition temperature increases, the kinetic energy of the sputtered particles is enhanced, as is their diffusion ability, which compacts the already deposited particles, resulting in a smoother and denser coating surface. Boron (B) in the target material is preferentially sputtered onto the substrate surface over titanium (Ti), causing the Ti-B-N coating to have a higher percentage of B than the target material. As the deposition temperature increases from 100 to 200 degrees C, the Ti content slightly decreases, and the B content slightly increases. When the deposition temperature reaches > 200 degrees C, there is no significant change in the Ti and B content. When the deposition temperature varies from 100 to 300 degrees C, h-TiB2 and Ti3B4 phases are detected in the coating; when the coating deposition temperature reaches 400 degrees C, only the h-TiB2 phase is detected. As the deposition temperature increases, the surface of the Ti-B-N coating gradually becomes smoother and denser, the hardness of the coating increases from 2 855 to 3 994 HV0.01, and the residual stress decreases from 0.9 to 0.3 GPa. When the deposition temperature is 400 degrees C, the coating is the smoothest and densest, with the highest hardness and the least residual stress. When the deposition temperature is 300 degrees C, the coating has the lowest friction coefficient and wear rate, which are 0.5 and 1.1 & times;10(-3) mu m3N(-1)mu m(-1), respectively, indicating the best wear resistance. This study indicates that Ti-B-N coatings deposited at 400 degrees C exhibit higher hardness, stronger adhesion, and lower tensile stress compared to those deposited at 300 degrees C. However, the friction rate significantly increases, suggesting that in this case, the primary factors influencing the frictional performance of the coating are not the hardness, adhesion strength, or internal stress. The average friction coefficient of the Ti-B-N coating deposited at 300 degrees C is 0.5, which is significantly lower than the coefficient of 0.8 at 400 degrees C. This demonstrates that under certain conditions, the friction coefficient is the main determinant of the frictional performance of the Ti-B-N coatings. By optimizing process parameters, such as the deposition temperature, it is possible to control the friction coefficient of the coating, thereby enhancing its overall frictional performance.

Three AlCrTiCN coatings, varying in carbon content, were fabricated on single-crystal silicon wafers and stainless-steel substrates by adjusting the C target power to 0, 50, and 100 W. The Al60Cr20Ti20 and C targets were connected to a direct-current pulse and radio-frequency magnetron sputtering power, respectively. The microstructures, chemical compositions, and mechanical and tribological properties of the coatings were characterized using X-ray diffractometry, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and nanoindentation. The primary phase of the coatings was the NaCl-type fcc-(Al,Cr,Ti)(C,N) phase. For the coating fabricated using a C target power of 50 W, the hcp-C3N4 phase was detected. However, upon further increasing the C target power to 100 W, the hcp-C3N4 phase disappeared, and no diffraction peaks corresponding to C or its compounds were detected. This observation may be attributed to the fact that a proportion of the C atoms is dissolved in the (Al,Cr,Ti)N crystal, while another portion is in an amorphous state. All the three coatings grew preferentially along the (111) crystal plane. As the C target power increased, the diffraction peaks broadened and the (111) texture coefficient decreased. The grain size also decreased, which might have been due to the increased amount of amorphous C, which hindered grain growth. The surface quality of the coatings improved with increasing C target power. The hardness of the coatings increased gradually from 10 GPa to 23.7 GPa, owing both to the solid solution effect of the C element and the reduced grain size, which lengthens the grain boundaries and hinders the movement of the dislocation. The H / E*, H-3 / E-*2 and We values also increased with increasing C target power and reached their largest values at C target power of 100 W. The adhesion strength first increased from 38.2 N at the C target power of 0 W to 43 N at the C target power of 50 W, subsequently decreasing slightly to 41.7 N at the C target power of 100 W. The adhesion strength first increased, probably because of the formation of a nanocomposite structure consisting of fcc-(Al,Cr,Ti)(C,N) and amorphous C, which prevented the generation and propagation of cracks at the interface between the substrate and coating. However, it decreased afterwards, which might be ascribed to the high internal stress generated by the growing amorphous C. With an increase in the C sputtering power, the friction factor first increased from 0.57 to 0.79, and then it decreased to 0.55. Unexpectedly, the friction factor did not drop with the C target power. This may be because the C3N4 phase formed in the coating with a C target power of 50 W deteriorated the lubrication effect of the graphite phase (sp2). Nevertheless, a significant drop in the wear rate was noted with the addition of C, and the coating fabricated using a C target power of 100 W exhibited the lowest wear rate (about 8.19x10-6mm3N-1m(-1)). This improvement can be ascribed to the enhanced mechanical properties associated with coatings fabricated using a higher C target power. Notably, the wear mechanisms of the three coatings differed. The coating fabricated using a C target power of 0 W failed primarily because of wear caused by oxidation, abrasion, and adhesion. The failure mechanism of the coating fabricated using a C target power of 50 W was primarily abrasive wear. As the C target power increased to 100 W, the coating was found to lose efficacy predominantly owing to adhesion wear because large amounts of lumps rich in Fe are found in the wear track. This study indicates that the addition of C to AlCrTiN coatings could improve their mechanical and tribological properties, and that these enhanced coatings could potentially find application in the fabrication of cutting tools.

Marine biofouling poses a persistent challenge for submerged mechanical equipment, leading to accelerated corrosion, operational inefficiencies, and significant economic losses. The accumulation of microbial communities on marine surfaces not only damages equipment but also substantially increases maintenance costs, creating a critical bottleneck for sustainable marine resource development. Addressing this issue through effective antifouling solutions has become a global research priority in marine engineering. Current antifouling technologies primarily encompass mechanical removal, ultrasonic cleaning, and protective coatings, with antifouling coatings emerging as the most widely adopted solution due to their cost-effectiveness, ease of application, and superior performance. There is a wide variety of antifouling coatings, each with distinct antifouling mechanisms. However, comprehensive reviews on the antifouling performance, advantages, and disadvantages of both traditional and novel antifouling coatings remain scarce. Thus, a comprehensive review is conducted on the research advancements of both traditional and novel antifouling coatings, such as natural antifoulant coatings, biomimetic coatings, self-healing coatings, etc. Their research status, antifouling mechanisms, and remaining challenges are discussed. Traditional antifouling coatings can be categorized into matrix-insoluble and matrix-soluble types. The former operate through the gradual release of embedded biocidal compounds that deter or eliminate fouling organisms. However, these coatings exhibit significant limitations, including short service lifetimes and complex application requirements, which restrict their widespread adoption in marine applications. Self-polishing antifouling coatings (SPCs), the most currently commercially successful matrix-soluble system, dominating 90% of the global market, utilize hydrolyzable polymer side chains to enable controlled antifoulant release. However, their uneven release kinetics (initial excess followed by insufficiency) compromises long-term performance, and their dependence on toxic biocides raises environmental concerns. In contrast to these traditional coatings that rely on biocidal agents, fouling-release coatings achieve antifouling effects solely through their low surface energy, preventing fouling organisms from firmly adhering. Under water flow, fouling organisms detach easily, providing excellent antifouling performance without harming the marine environment. However, these coatings perform poorly under static conditions, and their adhesion to substrate needs improvement. Natural antifoulant coatings derive their active substances from antifouling compounds secreted by plants and animals or their synthetic analogs. They reduce marine biofouling by inhibiting adhesion processes and interfering with microbial signaling systems. Compared to traditional antifoulants, natural antifoulants are less toxic and significantly reduce environmental impact. However, challenges such as broad-spectrum efficacy and long-term durability remain unresolved. Biomimetic coatings utilize micro-and nanostructures from self-cleaning natural surfaces (via 3D printing, laser etching, or transfer techniques) to achieve efficient and eco-friendly antifouling effects, showing high application potential. However, these coatings often suffer from low mechanical strength, poor adaptability, and high production costs. Self-healing marine coatings integrate specialized repair agents that autonomously mend surface damage, overcoming key limitations of conventional systems by extending service life and maintaining antifouling efficacy. Despite their potential for significant economic and performance benefits, commercialization challenges persist, including complex fabrication, high costs, and difficulties in scaling beyond laboratory prototypes. Photocatalytic coatings rely on photocatalysts to undergo redox reactions under specific light wavelengths, decomposing seawater and dissolved oxygen to generate reactive oxygen species (ROS). These ROS penetrate cell membranes, damage microbial DNA, and cause cell rupture, achieving antifouling through microbial inactivation. These coatings are safe, efficient, non-toxic, and pollution-free. However, their performance is highly dependent on UV intensity and light energy utilization, requiring further improvements in stability. Hydrogel coatings contain high water content (typically >70%, even >90%), forming a dense and dynamic hydration layer through hydrogen bonding between polymer chains and water molecules. This layer effectively blocks fouling organism attachment. However, their poor mechanical properties and weak adhesion limit broader applications. Despite the variety of marine antifouling coatings available, single mechanism approaches generally fail to meet the complex demands of marine environments, particularly regarding long-term efficacy, broad-spectrum performance, and environmental safety. To overcome these limitations, we propose the strategic integration of multiple antifouling mechanisms within hybrid coating systems. This synergistic approach aims to combine the advantages of different technologies while mitigating their individual weaknesses, paving the way for next-generation antifouling solutions that balance performance, durability, and ecological sustainability. The findings provide valuable insights for developing advanced marine coatings.

To investigate the influence of the concentrations of metal cations Ca2+, Mg2+, and Cl- in oil production water on the corrosion of Q235 steel, electrochemical impedance spectroscopy, and potentiodynamic polarization curves were used to assess the electrochemical properties of Q235 steel quantitatively. The results showed that the surface's sample gradually changed from active dissolution to passivation state with the increase of solution concentration, and the corrosion was significantly restrained at high ion content. When the solution medium concentration is 4.92 mol/LNaCl + 0.165 mol/L CaCl2 + 0.054 mol/L MgCl26H2O, Q235 steel performs optimally in terms of the corrosion property. X-ray diffraction and Raman analysis reveal that the corrosion products in the solution are mainly composed of calcium and magnesium ion complex carbonate (Mg3Ca(CO3)4), gamma-FeOOH, as well as iron oxides Fe2O3 and Fe3O4. Among them, Mg3Ca(CO3)4 and gamma-FeOOH, as a sedimentary layer, have excellent corrosion resistance, which does not exist at low ionic concentration (where there were iron oxides only) and gradually emerge with the rise of Mg2+ and Ca2+. This is crucial for the anticorrosion performance of Q235 steel and responsible for the active-passive corrosion transition behavior.

A novel composite waterborne coating, GO-PA-Zn/WEC, was successfully prepared by functionalizing graphene oxide (GO) nanosheets with divalent zinc ion Zn(II) and phytic acid (PA) as fillers through the hydrothermal method. FTIR, XRD, SEM-EDS, TEM, TGA, and XPS were employed to demonstrate the successful grafting and/or adsorption of Zn(II) and PA inhibitors on GO surface. Electrochemical impedance spectroscopy (EIS) tests proved that the low-frequency impedance value (|Z|0.01 Hz) of the steel with GO-Zn-PA/WEC coating (1.13 x 106 Omegacm2) was 5 times as high as that of WEC coatings (2.17 x 105 Omegacm2). Furthermore, the |Z|0.01 Hz (2.01 x 105 Omegacm2) even exhibited a magnitude approximately 20-fold of the conventional WEC coating (0.99 x 104 Omegacm2) after 14 days of immersion, demonstrating superior durability performance. Corrosion products beneath the coatings after 14 days of immersion were also analyzed by SEM, EDS, and XPS. Results reveal that the anticorrosion mechanism basing on synergistic effects of GO-Zn-PA fillers is as follows: (1) physical barrier effect of GO for the intrusion of corrosive species; (2) the protective layer formed by PA and Zn(II) in the defect area at the anode and cathode sites by producing sediment of Fe(3-x)/2HxPO4(3-x) and Zn(OH)2, respectively; (3) crosslinking structure of PA-Fe(II)-Zn(II) via chelation. This study provides a simple route for the design and manufacture of highly anticorrosive composite coatings.

To solve the problem that the cutting temperature rises sharply due to the high friction coefficient of AlCrSiN coated tools during dry cutting， which seriously shortens the service life of the tool， the tribological properties of the coating are improved by doping the sixth group Mo element in the AlCrSiN coating. AlCrSiN/Mo coating is prepared by high-power pulsed magnetron sputtering and pulsed DC magnetron sputtering composite coating technology under different deposition pressures， the coating composition and structure are adjusted， and the composition， structure， mechanical properties， and tribological properties of the coating are characterized by scanning electron microscopy， electron probe analyzer， X-ray diffractometer， nanoindentation， scratch tester， and friction and wear testing machine. The results show that with the increase of deposition pressure， the optimal growth orientation of the coating changes from （111） crystal plane to （200） crystal plane， and the microstructure becomes denser. The critical load of the coating gradually increases from 65.6 N to 82.0 N， but the deposition rate decreases linearly. When the deposition pressure is 1.6 Pa， the hardness and elastic modulus of the coating reach the highest values， which are 20.6 GPa and 394.3 GPa， respectively. The characteristic values H/E and H3/E*2 also reach the maximum， which are 0.052 GPa and 0.046 GPa， respectively， when the tribological properties of the coating are the best， and the friction coefficient and wear rate are 0.59 and 1.52×10-3 μm3·N-1·μm-1，respectively.

Multilayer coatings have garnered significant attention in recent years due to their exceptional properties, which are highly influenced by the deposition parameters such as N2/Ar flow ratio. In this study, three AlCrSiN/AlTiN multilayer coatings were fabricated using hybrid arc ion plating and DC magnetron sputtering with varying N2/Ar flow ratios to investigate their effects on coating properties. Structural analysis reveals an fcc-(Al,Cr,Ti)N solid solution with preferential (200) orientation. As the N2/Ar ratio increases, both grain size and surface roughness decreases. The mechanical properties show a non-monotonic trend, with peak hardness (35.10 GPa) and adhesion strength (54.54 N) achieved at a 4:1 N2/Ar ratio before declining at higher ratios due to the competing effects of grain refinement and target poisoning. The coating deposited at a 4:1 N2/Ar ratio demonstrates optimal mechanical performance, exhibiting the highest H/E* and H3/E*2 values, indicative of superior resistance to crack propagation and plastic deformation. Furthermore, this coating displays the best tribological and corrosion performance, achieving the lowest wear rate (8.2 × 10−6 mm3/N·m) and highest corrosion resistance. These enhancements are ascribed to its dense microstructure, increased hardness, and minimized surface defects.

The synergistic effect of calcium phosphate [Ca 3 (PO 4 ) 2 ] and benzotriazole [BTA] on corrosion inhibition of Q235 steel in 3.5 wt-% NaCl solution was studied by means of electrochemical, ultra-depth of field, scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Results indicated that the compound corrosion inhibitors of Ca 3 (PO 4 ) 2 and BTA provide excellent inhibition durability in long-term test, with the outstanding inhibition efficiency ( η ) up to 98.7% and the synergistic parameter ( s ) of 9.06 at the end of 28 days immersion. This is of crucial importance in practical application scenarios. Analysis of the corrosion products proves that this synergistic effect could be ascribed to the formation of a double-layered film on the surface of Q235 steel: the inner layer is cross-linked network structure between Ca 3 (PO 4 ) 2 and BTA with Fe 2+ through the lone pair electrons, while the outer layer is an adsorption film with strong adhesion, which well follows Langmuir adsorption isotherm and belongs to mixed adsorption. The double-layered film can effectively obstruct the infiltration of corrosive species and thus provide an outstanding anti-corrosion performance. This work provides a new strategy to achieve high anti-corrosion effect by using low-cost and mature inhibitors.

To investigate the effect of bias voltage variation on the microstructure, mechanical, tribological, and cutting properties of CrAlSiN coatings, six coatings were deposited under constant or linearly increasing bias voltages. Results show that all CrAlSiN coatings possess a singular fcc-(Cr,Al)N phase. Chemical compositions of the coatings change little with the bias voltage, while the grain size and surface roughness decrease gradually, leading to higher hardness and residual stress but lower adhesion strength. Compared with the coatings deposited at-160 and-200 V, the hardness of the bias-graded coatings decreases slightly, but their adhesion strength and fracture toughness are enhanced by 3-20% and 11-49% respectively, due to reduced residual stress. This improvement is attributed to the unique grain size gradient along the growth direction in the bias-graded coatings, which effectively reduces stress concentration and inhibits crack propagation. The bias-graded coatings exhibit a 44% longer cutting life compared to those deposited under constant bias voltages, with the cutting life increasing as the ultimate bias voltage rises. This enhanced performance is linked to their superior adhesion strength and toughness.

The microstructure evolution of AlCrTiN and AlCrTiSiN coatings containing 4, 6.8, and 10.6 at.% Si was studied at temperatures ranging from 800 to 1100 degrees C. The AlCrTiN coating exhibits a single-phase fcc-(Al,Cr,Ti)N structure, while the AlCrTiSiN coatings transition from a nanocomposite structure, composed of fcc-(Al,Cr,Ti)N and amorphous a-SixNy, to a fully amorphous structure as the Si content increases. The hardness and adhesion strength of coatings initially rise, peaking at 24 GPa and 44 N respectively, due to the formation of the nanocomposite structure. However, these properties decline as the coatings become fully amorphous. At elevated temperatures, severe oxidation leads to the gradual formation of layered oxides. Concurrently, phase transformation, spinodal decomposition, and crystallization occur within the nitride layer. The addition of Si enhances oxidation resistance by promoting the rapid formation of a dense and protective oxide layer, and by reducing nitrogen release and TiO2 formation. However, at 1000 and 1100 degrees C, the coating with 10 at.% Si exhibits slightly faster oxidation compared to the 6.8 at.% Si coating, as the increased Si content reduces the Al content, limiting the coating's ability to regenerate the protective oxide layer.

Si-modified NiAl coating has been studied by researchers due to its good performance in high temperature corrosive environment, but the effect of Si content on the high temperature oxidation resistance of the aluminide coatings has been seldom studied. To figure out this issue, three modified NiAl coatings with different Si contents were prepared by varying the Si contents 8wt%, 17wt% and 30 wt% in the slurry. Phase structures and microstructures of the simple NiAl coatings and three Si-modified NiAl coatings before and after oxidation were analyzed by XRD, SEM and EPMA, etc. The results show that the delta-Ni2Al3 and ss-NiAl are the primary phases of the four aluminide coatings. Si mainly locates in the upper zone of the Si-modified NiAl coatings in the form of silicides as CrSi2, Cr5Si3 and Ni2Si. After oxidation at 1000. for 500 h, the simple NiAl coating has the maximum mass gain of 1.93 mg/cm(2), while the Si-modified NiAl coating with Si content of 8wt% has the smallest mass gain. The dopant of Si into NiAl coatings can promote the formation of protective alpha-Al2O3 film, retard the outward diffusion of refractory metal elements and improve the surface quality of the oxide film, resulting in reduced oxidation rate. However, the addition of Si reduces the Al content on the surface layer of the coating and may make the coating insufficient of ss phase to maintain the selective oxidation of Al in the later period of long- time oxidation. Therefore, when the Si content is 8wt%, the Si-modified NiAl coating possesses the best oxidation resistance.

For further enhancing the hot corrosion resistance of the NiCrAlY coating,the NiCrAlY/NiAl/Al coating(coating A)and the NiCrAlY/Pt/NiAl/Al coating(coating B)were deposited on the surface of DZ125 alloy by arc ion plating technology,and then the gradient coating structure with gradually changing composition was formed by vacuum diffusion annealing.The modified element Pt was introduced into the coating to enhance the hot corrosion resistance of the coating,and the hot corrosion behavior of two coating systems in different mixed salts at 900 ℃ was studied.Additionally,the microstructure,phase composition and element distribution of the coating after hot corrosion were ana-lyzed by SEM,EDS,XRD and EPMA.Results showed in a mixed salt of K2SO4+Na2SO4 at 900 ℃,the extensive spalling of the oxide film occurred on the surface of coating A.Pt in coating B inhibited the segregation of S at the coating/oxide film interface,and enhanced the adhe-sion of the oxide film.In the mixed salt of NaCl+Na2SO4 at 900 ℃,the Cr element and O element of coating A underwent outward diffusion and inward diffusion,respectively.The outward diffusion of Cr was easy to react with S to form a harmful phase CrxSy.In contrast,the Pt in coating B inhibited the outward diffusion and inward diffusion of Cr and O elements.Overall,the addition of Pt layer between NiCrAlY and NiAl layers significantly enhanced the hot corrosion resistance of the NiCrAlY coating in mixed salts.

Corrosion inhibitors are widely used because they have the characteristics of trace and high efficiency,can prevent metal corrosion,while maintaining the physical and mechanical properties of the metal unchanged,and easy to use. Traditional metal corrosion inhibitors have poor biodegradability,toxicity and are easy to cause environmental pollution. Based on the concepts of environmental protection,sustainable development and green chemistry,the use of traditional metal corrosion inhibitors has been severely restricted,and the research on corrosion inhibitors is gradually shifting to environmentally friendly substances. In this paper,green environmental protection corrosion inhibitors were divided into single system corrosion inhibitors and compound system corrosion inhibitors,and the research progress in recent years were reviewed. Furthermore,the advantages and disadvantages of various types of corrosion inhibitors were classified and summarized,and the current status and research direction of environmentally friendly corrosion inhibitors were prospected.

Deposition pressure is an important process parameter for coating preparation. To study its influence on the microstructure, mechani-cal properties and high-temperature oxidation resistance of AlCrTiSiN nanocomposite coatings, two types of AlCrTiSiN nanocomposite coatingswere prepared using RF magnetron sputtering and pulse DC magnetron sputtering composite technologies at different deposition pressures (0.6, 0.8 Pa). Comparative analyses of the structure and properties of two types of coatings were performed using X-ray diffractometer (XRD), scan-ning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) and nanoindenter. Results showed that the phase structure of the coatings prepared under two kinds of deposition pressures was fcc-(Al, Cr, Ti) N, which grew preferentially along the (111) crystal plane. However, the larger (111) texture coefficient of the coating prepared at 0.8 Pa indicated that the preferred orientation was more pronounced. Compared to the coating prepared at the deposition pressure of 0.8 Pa, the coating prepared at 0.6 Pa was characterized by finer surface particles, a denser coating and better mechanical properties, including better resistance to elastic and plastic deformation, as well as better adhesion between film and substrate. This was partly because the deposited particles reached the substrate with greater energy at the lower deposition pressure. On the other hand, a thicker and softer Si3 N4 phase might have been present in the coating prepared at 0.8 Pa. After oxida-tion at 900℃ for 6 h, a continuous and dense Al2 O3 mixed oxide film had formed on the surface of the coating, effectively preventing the diffu-sion of oxygen into the coating and protecting the coating under the oxide film. With the increase in deposition pressure from 0.6 to 0.8 Pa, the oxide particles increased, the thickness of the oxide film increased, and the high-temperature oxidation resistance decreased.

Synergistic effects of a novel Cu51Hf14 inoculant and Zr element on the microstructure, mechanical and damping properties of Cu-Al-Mn shape memory alloy were investigated. The results showed that grains of the alloy could be significantly refined due to the heterogeneous nucleation of Cu51Hf14 and the pinning effect of AlCu2Zr particles on grain boundaries (GBs), the martensite lath was also greatly refined. Mechanical properties were improved obviously, the alloy with the smallest grain size showed the highest tensile strength and elongation. This attributed to grain refinement, increasing difficulty of grain coordination deformation, decreasing mobility of martensite variants and the pinning effect of AlCu2Zr on dislocation. The compound refining alloys possessed high room-temperature damping owing to the increased interface density and the uncoordinated deformation of AlCu2Zr and Cu-Al-Mn matrix. While its high-temperature damping was lower than that of the inoculated alloy because of the decreasing martensite content caused by the increasing GB influence zone and the precipitation of AlCu2Zr.

The inhibition effect of benzotriazole (BTA) with the increase of concentration for 20SiMn steel in 3.5 wt% NaCl solutions was investigated by electrochemical methods, Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS) and Density Functional Theories(DFT). Results indicate that BTA could suppress the corrosion of 20SiMn steel through chemisorption but with a limited inhibition efficiency (around 60%). DFT calculated results show that the chemisorption of BTA has noticeable effects on the charge distribution of the whole BTA molecule, as well as that of N atom which bonds with Fe atom, but has little influence on those of Fe atom in N-Fe bond and Fe(1 1 0) surface where BTA molecules adsorb. The DFT calculated Density of States (DOS) peaks of N atom in N-Fe and those of BTA molecule become lower after the adsorption, and the location of DOS peaks move far away from the Femi surface, implying a more stable structure. As to Fe atom in N-Fe bond and Fe(1 1 0) surface, neither height nor locations of the DOS peaks change,which is crucial for losing electrons of metallic matrix and thus responsible for the limitation of BTA inhibition effect.

The synergistic inhibition effect of sodium phytate (PA) and benzotriazole (BTA) on 20SiMn steel in 3.5 wt-% NaCl solutions was studied using electrochemical methods, SEM, FTIR, XPS and quantum chemical calculations based on density functional theory (DFT). Results indicate that a protective bi-layer film is formed with the presence of the mixture of PA and BTA: the inner layer consists of iron oxides(,) while the outer one is an adsorption layer of BTA and PA. Based on the analysis of XPS and DFT, the function of BTA belongs to chemisorption, while that of PA obeys Langmuir adsorption isotherm and could be mainly assigned to physisorption. The inhibition efficiency of the mixture inhibitor is 99.12%, with a synergism parameter of 3.62, which could be ascribed to a cross-linking structure containing more BTA promoted by PA through hydrogen bonds.

Bias voltage has great influence on the microstructure and properties of multilayer coatings, but it is endowed less attentions compared with modulation periods. In this work, effects of bias voltage ranging from -120 V to -210 V on the microstructure and properties of the AlCrN/AlTiN multilayer coatings are investigated. Results show that the multilayer coatings possess fcc-(Al,Cr,Ti)N singular phase, and grow preferentially along the (111) plane, but the texture coefficient of the (111) plane drops greatly at -210 V. Surface roughness decreases firstly and then increases with the bias voltage. Conversely, the hardness increases gradually to the maximum value 33.0 GPa at -180 V, and then decreases to 26.4 GPa at -210 V caused by the texture variation and coarse structure. The adhesion strength decreases gradually with the bias voltage due to augmented residual stress. The friction coefficient and wear rate drop firstly and then increase at -210 V. Abrasion, oxidation and adhesion wear are primarily responsible for the failure of the coatings at mediate bias voltage, while spallation accelerates the failure of the coatings at -120 V and -210 V caused by their poor microstructure and mechanical property.