AA6061-T6 Aluminum Alloy Research Articles

Heat generation, plastic deformation and residual stresses in friction stir welding of aluminium alloy

The interactions among thermal history, plastic deformation and residual stresses in the friction stir welding (FSW) process under different welding parameters have been widely considered a crucial issue and still not fully understood. In the present study, a novel three-dimensional fully coupled thermo-mechanical finite element (FE) model based on Coupled Eulerian-Lagrangian approach (CEL) has been developed to simulate the FSW process of aluminium alloy AA 6082-T6 and to analyse the thermo-mechanical interaction mechanisms under different welding conditions. The numerical model successfully simulates the plunge, dwell, and welding steps in FSW and captures the evolution of temperature, plastic deformation, and residual stresses in the welded joint. The obtained results were validated by experimental testing with observed cross-weld thermal history, optical macrography and residual stress measurement using the neutron diffraction technique. The results reveal that the tool rotation speed governs the temperature evolution; the peak temperature increased from 740 to 850 °K when the tool rotation speed rose from 800 to 1100 rpm. The rotational speed also affected the plastic deformation, material flow, and the volume of material being stirred during the welding process. Higher plastic deformation is formed in the stirring zone by increasing the tool angular velocity. This behaviour led to an increase in the stirring effect of the welding tool, reduction of the tunnel defect size and enhancing the quality of weldments. The distribution of residual stresses in different zones of the FSW joints has been found to have an M-shaped profile. A significant tensile residual stress is characterised in the edge of the nugget zone in both longitudinal and transverse directions, balanced by compressive stresses in the thermo-mechanically affected zone, heat-affected zone and base metal. The presented FE modelling provides a reliable insight into the effects of the welding parameters on the weld quality of FSW joints and process optimisation with minimised experimental trials.

Casting and forming of nano hard aluminum oxide film on the modified 6061 Al alloys for NARSSCube satellite structure

This research focuses on metal additive manufacturing (MAM) and examines the impact of alloying materials on the anodized produced layer, placing particular emphasis on its use in the construction of the NARSSCube satellite's frame. To enhance the AA6061-T6 Al alloy's mechanical and physical qualities, Mg, Mn, Si, and Cr concentrations were changed. As a result, seven different alloys were cast, and their mechanical and physical characteristics were assessed. It is essential to anodize aluminum alloy AA6061-T6 in H2SO4 solution in order to produce an aluminum oxide film (AOF) that increases corrosion and wear resistance. This study looked into how the chemical composition of the AA6061-T6 aluminum alloy, particularly Mn, affected the production of the nano hard aluminum oxide film (NHAOF) at fixed anodization conditions of 4 °C and 20 V. Calculations were made on the thickness variation at various operating voltages throughout the anodizing process. The differences in NHAOF thickness were investigated using optical and scanning electron microscopes. Finally, anodizing the alloy with low Mn Wt.% (0.005 wt% S6) at 4 °C, 20 V, and a duration period of 120 min in a 10 % H2SO4 solution produced the oxide coating with the highest thickness (53 μm) and high-performance attributes. An increase in the hardness ratio, resistance to plastic indentation, and elastic recovery are all results of the surface's harder (5.86 Gpa) than the un-anodized sample's (1.18 Gpa) surface.

Agro-industrial wastes as corrosion inhibitor for 2024-T3 aluminum alloy in hydrochloric acid medium

Aluminium corrosion in hydrochloric acid media is a huge challenge in the chemical industry; hence, creating green and more efficient inhibitors is an urgent task. Furthermore, the increasing amount of solid waste and its disposal consequences has been a major economic and environmental problem. Therefore, this study aims to determine the protective effect of coconut shell as a potential corrosion inhibitor for AA2024-T3 aluminium alloy in 1 M hydrochloric acid solutions using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques. The results show that the inhibition efficiency increases with an increase in the coconut shell concentration, and the maximum inhibition efficiency reaches 97.91% at 1 g/L. The potentiodynamic polarization study shows that the inhibitor acts as a mixed-type corrosion inhibitor. The adsorption of the inhibitor obeyed the Langmuir adsorption isotherm. The surface characterization confirmed the presence of barrier layers covering the aluminum surface. The mechanical properties were also determined and discussed. As compared to the wide range of reported corrosion inhibitors in the literature, the coconut shell has shown to be highly effective for AA2024-T3aluminium alloy. Therefore, it can be suggested that coconut shell waste is a potential corrosion inhibitor for AA2024-T3aluminium alloy in the chemical industry.

A Comparative Study of Self-Piercing Riveting and Friction Self-Piercing Riveting of Cast Aluminum Alloy Al–Si7Mg

Abstract Cast aluminum alloys are promising materials that can simplify the manufacturing process of automobile body structures. However, the low ductility of cast aluminum poses significant challenges to existing riveting technologies. In the present work, dissimilar AA6061-T6 aluminum alloy and Al–Si7Mg cast aluminum were joined by self-piercing riveting (SPR) and friction self-piercing riveting (F-SPR) processes to reveal the effect of friction heat on rivetability of low-ductility cast aluminum alloys. The joint macro-morphology, microstructure, peak tooling force, microhardness distribution, tensile-shear, and cross-tension performance of the two processes were comparatively studied. Results indicated that the in-situ softening effect of friction heat in the F-SPR process could effectively improve the ductility of cast aluminum, avoid cracking, and reduce the tooling force by 53%, compared to the SPR process. The severe plastic deformation and friction heat induced by rivet rotation results in refined equiaxed grains of aluminum near the rivets and solid-state bonding between aluminum sheets in the rivet cavity. The F-SPR joints are superior to SPR joints in both tensile-shear and cross-tension performance due to the avoidance of cracking, increase of mechanical interlocking, and solid-state bonding of interfaces. Significantly, when Al–Si7Mg is placed on the lower layer, the peak tensile-shear and cross-tension loads of the F-SPR joints are 7.2% and 45.5% higher than the corresponding SPR joints, respectively.

Combined effect of surface pretreatment and nanomaterial reinforcement on the adhesion strength of aluminium joints

Nowadays, it is known that adhesive and cohesive forces should be developed in order to improve the mechanical performance of adhesive joints. In this context, while the adhesive forces are improved with surface pretreatments applied to the adherends, the adhesive and cohesive forces are improved with the nanomaterial reinforcement to the adhesive. For this purpose, in this study, AA7075-T6 aluminium alloy adherends were combined with epoxy adhesive as a single lap joint. As a preliminary study, abrading and FPL-etching (Forest Products Laboratory) surface pretreatments were applied to aluminium alloy adherends and after two different surface pretreatments, the changing surface morphology (with optical microscope, contact angle, profilometer measurements) and shear strength were compared. With abrading and FPL-etching surface pretreatments, an increase of 40.83% and 69.63%, respectively, was determined in the shear strength compared to untreated adhesive joints. After the preliminary study, in order to increase the mechanical performance of the adhesive joints, nano sized ANP (alumina nanopowder), MWCNT (multiwalled carbon nanotubes) and SNP (silica nanopowder) were added to the adhesive. Thus, it was investigated how the combined effect of different surface pretreatments and nanomaterial types at various reinforcement ratios changed the shear strength of the adhesive joints. After shear tests, significant increase in shear strength was observed in FPL-etched adhesive joints compared to abraded adhesive joints in all reinforcement nanomaterial types and reinforcement ratios. And also, significant improvements in the shear strength of adhesive joints were determined in all types of nanomaterial reinforcements. The highest shear strength was obtained at 10.0 wt % SNP reinforcement with 104.32% improvement in FPL-etched adhesive joints compared to nonreinforced FPL-etched adhesive joints. The evaluation of shear strength was supported by the failure images taken from the fracture surfaces after shear tests, and it was determined that the failure type was changed from adhesive to cohesive with nanomaterial reinforcement compared to nonreinforced adhesive joints.

Residual Stress Redistribution Analysis in the Repair Welding of AA6082-T6 Aluminum Alloy Joints: Experiment and Simulation.

Residual stress has a three-dimensional scale effect (length, depth, and width) in the process of repair welding, which has a detrimental impact on the service of the aluminum alloy welded structures in high-speed trains. This paper aims to systematically analyze the effects of the repair welding dimension on the residual stress redistribution and obtain the optimal repair welding principles. A combination of blind-hole drilling method and stress linearization in BS7910 was adopted to investigate residual stress redistribution under various repair welding dimensions. The results indicate that repair welding dimension was in accordance with the principle of “SNL (shallow, narrow and long)” and the optimal repair length, depth, and width of butt joints in this study were 15t, 0.25t, and t, respectively (t is the plate thickness of butt joints).

Investigating the multiscale effects of a novel post–weld composite processing treatment on minimizing weld softening in AA6061-T6 Al–alloy

The fusion welding of heat-treatable AA6061-T6 aluminum alloy results in significant joint softening which results in the ultimate tensile strength (UTS) and elongation (El) of the welded joint only reaching up to 60–70% and 40–50% of the base metal (BM), respectively. A post–weld composite processing treatment (PWCPT) that uses solution treatment (ST), artificial aging treatment (AT) and cold rolling (CR) has been proposed in this study to mitigate this issue. The effect of different composite process sequences and parameters on the microstructural characteristics and mechanical properties of the joints were investigated. The results show that the formation of the fine-grained microstructure in the fusion zone (FZ) and abnormal sandwich microstructure in the heat-affected zone (HAZ) was highly dependent on the dislocation density and fraction of the insoluble phases. By clarifying the strain characteristics of the joints, a strategy was developed to optimize the homogeneity of the microhardness distribution which improves joint ductility. The optimal PWCPT involved the ST and AT for the AA6061-T6 joint that was produced by tungsten inert gas (TIG) welding with filler wire, with subsequent cold rolling of the weld reinforcement to achieve a rolling reduction of 1.2 mm. The PWCPT could completely eliminate joint softening and improved the joint UTS and El to 100% and 88.6% of the BM, respectively. By systematically expounding the evolution law of microstructure and mechanical properties of the welded joint under the coupling of thermal and mechanical, the strengthening mechanism of the PWCPT is revealed.

Influence of Plug Rotational Speed on Microstructure and Texture of the Recrystallized Zone of a Friction Plug Weld Joint for AA6082-T6.

Experiments of friction plug weld AA6082-T6 aluminum alloy hole defects were carried out by using the method of friction auxiliary heating between the shaft shoulder and base metal. The grain refinement of the joint’s re-crystallized zone was significant, and there was obvious preferred orientation. Under the condition of other constant parameters, the rotational speed of the plug increases as the grain size of RZ increases and the component of High Angle Grain Boundaries decreases. The effect of a high deformation rate on dynamic re-crystallization is greater than that of high deformation temperature. The deformation texture component increased from 1600 r/min to 2000 r/min, while the re-crystallization texture component increased first and then decreased.

Comparative study of microstructure and mechanical properties using a novel filler rod ER 4943 and autogenously butt welded joint during laser welding of AA 6061-T6 in 1G position

A 4 mm thick heat-treated aluminum alloy AA 6061-T6 has been butt welded in 1 G position using a 12-kW disk laser. A novel high magnesium content filler rod ER 4943 belonging to the 4xxx series of aluminum alloys has been used to investigate its effects on microstructure, mechanical properties and alloying elements segregation in the fusion zone. The results have also been compared with an autogenous laser butt welded joint case. A solidified microstructure has been analyzed by EBSD. It was found that additional solute content brought by filler rod into the molten pool caused a higher proportion of equiaxed grain zone after solidification due to an enhanced constitutional supercooling ahead of solid/liquid interface. For an autogenous butt welded joint, the columnar morphology sustained for a longer period and a narrower equiaxed grain zone were observed. Point analysis by an EDS revealed a higher retention of magnesium and silicon inside the solid solution with filler rod welding. In addition, the area map of magnesium also observed a denser distribution of magnesium inside the fusion zone. Both hardness and tensile strength of filler rod welded joint were higher than without filler rod welding. It is believed that a higher proportion of equiaxed grains and additional solute content within the solid solution are the primary causes of higher mechanical properties owing to hampered dislocation motion. The much desirable results obtained in terms of microstructure and mechanical properties could be of great significance to the welding industry.

Effect of Welding Parameters on Mechanical Properties and Microstructure of Friction Stir Welded AA7075-T651 Aluminum Alloy Butt Joints.

The aim of this study was to examine the mechanical properties of 5-mm-thick AA7075-T651 alloy using three different welding velocities, 50, 75 and 100 mm/min, and four various sets of tool rotation speeds: 400, 600, 800 and 1000 rpm. All obtained joints were defect-free. In all cases, the values of UTS exceeded 400 MPa, corresponding to 68.5% minimum joint efficiency. The highest value of 447.7 MPa (76.7% joint efficiency) was reported for the joint produced via 400 rpm tool rotation speed and 100 mm/min welding velocity. The SZ microstructure of the strongest joint was characterized by a 5.2 ± 1.7 μm grain size and microhardness of approximately 145 HV0.1. The TMAZ/HAZ interface was identified as the low-hardness zone (105–115 HV0.1, depending on parameters), where the failure of the tensile samples takes place. The fracture mechanism is dominated by a transgranular ductile rupture with microvoid coalescence.

The effect of Argon Shield Gas and Cold Air for Friction Stir Welding of Ceramic-reinforced Aluminium Matrix Composite and Aluminium Alloy

A dissimilar joint between friction stir welded ceramic-reinforced C35 aluminium matrix composite and AA7075-T6 aluminium alloy has some difficulties. For fusion welding of aluminium, a shielding gas always has to be used to achieve the required welding joint quality, but in the case of Friction Stir Welding (FSW) no shielding gas or filler material is required for welding aluminium alloys. To achieve a good welding joint between super strength aluminium alloys and ceramic-reinforced aluminium matrix composites some sort of support is needed. In this study, the effect of blowing argon gas and cold air (0 °C) was investigated with regards to the quality of the welding. For the experiment a cylindrical pin tool, a different feed and a constant rotation speed were utilized along with a marble table to avoid harmful heat conduction. For evaluations, hardness and tensile tests examinations were carried out to classify the mechanical properties of the joint. Experimental results showed that the blowing of gas and cold air having a positive effect on the welded joint quality and also for the weld face. Additionally, the optimal welding traveling speed and the temperature of the air blown was determined.

A novel post-weld composite treatment process for improving the mechanical properties of AA 6061-T6 aluminum alloy welded joints

The welded joint for a heat-treated aluminum alloy AA 6061-T6 showed softening in the fusion zone (FZ) and the heat-affected zone (HAZ). This paper proposed a post-weld composite treatment process that overcame the joint softening by coupling the solubilization treatment (ST), aging treatment (AT), and cold rolling (CR). Three post-weld composite treatment processes were investigated to reveal the effect of the interaction between precipitation hardening and work hardening on joint mechanical properties. Experimental results showed that the post-weld “ST-AT-CR” composite treatment process could improve the microhardness of the FZ and HAZ to the level of the original base metal (BM), and the joint strength and ductility could reach up to 100 % and 67 % of the BM, respectively. On the other hand, it was also observed that the post-weld “CR-ST-AT” composite treatment process could make the joint softening more serious. The higher pre-existing dislocation density by the CR process would provide more diffusion channels for the solute atoms during the ST-AT process and promote the over-aging of strengthening phases, while the ST-AT process would significantly reduce the pre-existing dislocation density.

Development of friction stir powder deposition process for repairing of aerospace-grade aluminum alloys

This paper presents development of a novel friction stir powder deposition (FSPD) process for potential repairing applications of aerospace-grade aluminum alloy AA6061-T6. Powder form of the deposition material was thermo-mechanically processed at a temperature below its melting point. Influence of various process parameters on thermal cycles, deposition quality, deposition height, microstructure, and mechanical properties have been studied. Higher degree of deformation resulted in a dynamically recrystallized fine-grained microstructure which gave better mechanical properties. EDS study revealed uniform distribution of the major alloying elements throughout the deposition. Best quality deposition showed maximum microhardness and wear rate 0.84 and 1.07 times respectively than the substrate AA6061-T6 alloy. FSPD process is found to be capable of depositing maximum height of 0.45 mm, maximum deposition efficiency of 22% with an energy consumption of 73.7 J/mm 3 per unit deposition material consumption. Moreover, it used current in the range of 5-7 Ampere. This research shows that FSPD process can provide considerable cost and energy savings over fusion-based additive manufacturing processes making it a viable alternative for repairing aerospace-grade aluminum alloys. • Developed friction-stir powder deposition as a solid-state AM process for aerospace-grade Al alloys. • Max. deposition height: 0.45 mm; deposition efficiency: 22%; Avg. peak temperature: 293 °C. • Higher deformation gave dynamically recrystallized fine-grained microstructure. • Uniform distribution of alloying elements in the deposition. • Deposition microhardness and wear rate are 0.84 and 1.07 times than substrate AA6061-T6.

Electrodeposition of silane/reduced graphene oxide nanocomposite on AA2024-T3 alloy with enhanced corrosion protection, chemical and mechanical stability

Hydrophobic silane/reduced graphene oxide (rGO) nanocomposites were successfully constructed on an AA2024-T3 aluminum alloy surface using a facile co-electrodeposition process. The composition and morphology were characterized by ATR-FTIR, XRD, Raman spectroscopy, EDX, XPS and SEM. The results revealed that the implanted GO nanosheets were partially reduced and successfully covalently bonded with silanol groups to fabricate a more compact and denser coating. Electrochemical measurements demonstrated that the electrodeposited silane/rGO nanocomposite markedly decreased the corrosion rate of the AA2024-T3 alloy in 3.5 wt% NaCl solution. The protection efficiency was maintained over 96% after 120 h of exposure, presenting excellent chemical stability. Meanwhile, a sand paper abrasion test was performed to evaluate the mechanical robustness and the contact angle was reduced by only 4.5° after 150 abrasion cycles. The excellent anti-corrosion property and mechanical robustness, along with the feasible electrodeposition procedure, show its great potential for industrial applications.

Metallurgical, mechanical and corrosion characteristics of vibration assisted gas metal arc AA6061-T6 welded joints

Microstructure, mechanical properties and corrosion performance of gas metal arc AA6061-T6 aluminum alloy welded joints under the effect of mechanical vibration during welding have been investigated. The vibration frequencies, f used in this study were in the range of 0-500 Hz. Subsequently, several experiments were performed including microstructural observation, microhardness measurements, tensile tests, fatigue crack growth tests combined with fractography study and electrochemical polarization tests in 3.5% NaCl solution. Results indicated that the application of mechanical vibration increased tensile strength of the welded joints up to 83.3 % higher than the weld without vibration achieved at a frequency of 300 Hz. It was found that the strengthening mechanisms in the vibrated weld joints occurred mainly by the grain refinement of columnar dendritic and equiaxed dendritic microstructures in the weld metal region. Such microstructures could contribute to fatigue crack growth inhibition in the weld metal. Based on electrochemical corrosion tests, the vibration assisted weld joints were found to have better corrosion resistance than as-welded weld joint. The improved corrosion performance was likely attributable to suppression of intermetallic compound formation such as Mg2Si by mechanical vibration during weld solidification.

Calibration of the Elasto-Plastic Properties of Friction Stir Welded Blanks in Aluminum Alloy AA6082

In recent years remarkable efforts have been devoted to the study of the formability of tailored blanks processed by friction stir welding (FSW) by means of numerical and experimental approaches. This study aims to perform an inverse analysis to calibrate the constitutive law of FSW blanks produced with different parameters. The evaluated mechanical behavior will be employed in future studies to investigate the formability of such elements by single point incremental forming. This study analyzes friction stir welded blanks in aluminum alloy AA6082-T6 produced with different advancing velocities and tool rotational speeds. Coupons for tensile testing have been cut and collected from the FSW blanks. The longitudinal dimension of the coupons was perpendicular to the tool advancing direction, with the welding centerline located at the middle point of the coupon. From the same welded blanks further coupons have been collected to conduct microhardness testing of the cross-section in the welding zone. Data from digital image correlation (DIC) have been adopted to detect the zones of local variation of the mechanical properties related to the peculiar microstructure determined by friction stir welding. In particular, the data were used as input to feed an iterative numerical routine to calibrate the constitutive law variable as a function of the distance from the welding centerline.

Temperature Analysis of Friction Stir Welding (AA6061-T6) with Coupled Eulerian-Lagrangian Approach.

For Friction Stir Welding (FSW), several simplified FEM models have been developed to explain key parts of thermal-mechanical phenomena. In this study, to simulate the FSW process of the AA6061-T6 aluminum alloy, a thermo-mechanical 3-D finite element model based on the Coupled Eulerian-Lagrangian (CEL) approach is used. The CEL method combines the benefits of both the Lagrangian and Eulerian approaches, allowing it to solve large-scale deformation issues. The Abaqus/CAE software is used to simulate the stages of the FSW process using the Johnson–Cook material law and the Johnson-Cook failure model. The CEL approach is used to estimate process parameters based on the model's boundary conditions of the 3-D rigid tool. Thermocouples were installed in the appropriate positions on the AA6061-T6 plate, and temperature is correlated with the simulation results. The temperature generated during the plunging, dwelling, and welding stages of the FSW of AA6061-T6 is 80% to 90% of the melting temperature being evaluated. The experimental data was obtained from the HMT made CNC (Siemens) operated VMC and the same is compared with the results obtained from the overall FEM simulation.

Influence of hexagonal boron nitride additive nanocutting fluid on the machining of AA6061-T6 alloy using minimum quality lubrication

The extravagant usage of cutting fluid affects the environment and operator's health badly. Therefore, a well-established cooling technique minimum quantity lubrication was used in the present investigation in which environment-friendly cutting fluid based on soya bean oil was used. The investigation of the machining performance of soya bean oil-based hexagonal boron nitride nanofluid under minimum quantity lubrication during the milling of aluminum alloy AA6061-T6 was carried out to optimize the machining parameters for minimizing the cutting force and surface roughness. The machining results are further analyzed using Taguchi single-objective optimization, regression and Analysis of Variance (ANOVA), and multi-response optimization using Desirability Function Analysis (DFA). Furthermore, the mathematical models are developed for cutting force and surface roughness for milling under minimum quantity lubrication using regression analysis, and the models are found to be significant with minimum error. The nanofluid with 0.25 wt% nanoparticle concentration yielded minimum force and surface roughness at optimized machining parameters of 100 m/min, cutting speed, and 400 mm/min feed rate. However, the soya bean-based hexagonal boron nitride nanofluid minimum quantity lubrication machining yields better results than the flood-cutting condition.

PENGARUH FREKUENSI GETARAN TERHADAP SIFAT FISIS DAN MEKANIK PADA SAMBUNGAN LAS MIG ALUMINIUM PADUAN AA 6061-T6

AA 6061-T6 aluminium alloy is one of the 6xxx series that is widely used in engineering, especially automotive, aircraft, piping, and shipbuilding industries because it has many advantages. Despite AA 6061-T6 has a relatively good weldability, the strength of the weld joints is lower compared to its AA6061-T6 base metal. Therefore, this study aims to improve mechanical properties of metal inert gas (MIG) welded AA 6061-T6 aluminium alloy plates such as hardness and tensile strength by introducing engineering vibration during welding at a frequency of 100 Hz. The MIG welding process was conducted using current (I), voltage (E) and welding speed (v) of 120 Ampere, 20 Volt and 12 mm/minute respectively with filler metal used was ER5356. Results showed that the ultimate tensile strength of the weld joints increased under vibrational treatment with the tensile strength achieved 172.02 MPa which was 49% higher compared to conventional weld joint. The higher strength of the vibrated weld joints could be linked to the weld microstructure which consisted of fine grained equiaxed-dendritic structures.

Effect of Cerium Tartrate on the Corrosion Resistance of Epoxy Coating on Aluminum Alloy and Its Mechanism

The inhibition effect and mechanism of cerium tartrate (CeTar) as a pigment in epoxy coating on AA2024-T3 aluminum alloy in 3.5% NaCl solution were studied. Two kinds of coatings were applied on the substrate, including a single-layer epoxy coating with CeTar distributed uniformly and a double-layer coating composed of an inner layer doped with CeTar and an outer layer with no CeTar. The protective performances of the coatings were assessed by a Machu test and an Electrochemical impedance spectroscopy (EIS) technique. The corrosion inhibition mechanism of CeTar in the coating was analyzed with X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICP-MS) and Fourier transform spectroscopy (FTIR). The results show that the addition of CeTar can evidently improve the protective performance of the epoxy coating for a long time (>520 d). This might have relationship with the modification effect on the epoxy coating by cerium salts, and also may be due to the synergistic inhibitory effect by tartrate group and cerium ions on the alloy substrate after their continuous releasing to the coating/alloy interface and forming of a protective film. The double-layer coating provides similar protective properties to the single-layer coating. This suggested that creating a protective film on the aluminum alloy substrate could result in a greater contribution to improving the protection performance of the coating.