Corrosion Fatigue Research Articles

Review on Corrosion Behavior, Fatigue Behavior and Fracture Toughness of AL Alloy MMCS

In order to improve fuel efficiency, structural materials like Aluminium Alloy Metal Matrix Composites (MMCs) with high specific strengths are currently looked for. These materials are mostly used in the automobile and aircraft industries. In order to increase the elastic modulus, wear resistance, corrosion resistance, and fracture toughness of composite materials, researchers have attempted to choose reinforcements for composites effectively.Numerous physical and mechanical tests are important due to the constantly rising performance requirements in different applications. In order to describe and comprehend the performance of these materials, testing of composites is necessary. Tensile, compression, impact, bend, shear, corrosion, fatigue, and fracture toughness tests are among the experimental procedures used to test composite materials.Among the above mechanical testings, this paper aims to review and analyse a wide range of corrosion and fatigue behaviours with various types of reinforcements in aluminium alloy MMCs as these tests are significant in service life and performance aspects. In this paper efforts are made in order to understand how the trend evolves along with the reinforcements used and the technique followed.

Time-dependent fatigue reliability estimation and optimal design of scraper chains under corrosive wear effect

Fatigue damage is one of the main failures of the scraper chain. Moreover, corrosive wear has a detrimental effect on fatigue crack propagation. It is so essential to study the fatigue reliability of the scraper chain considering the interaction of corrosive wear and fatigue. This paper is intended to propose a reliability-based estimation and optimal design of the scraper chain considering the performance degradation of the scraper chain under the interaction of corrosive wear and fatigue. First, the dynamic model of the scraper conveyor is established based on the finite element method. Second, Paris Low is used to empirically describe the occurrence of cracking with corrosion effects. Furthermore, the time-dependent reliability of scraper chains under the interaction of the corrosive wear and fatigue crack propagation is addressed by the fourth-moment saddlepoint approximation (FMSA) method, and the reliability-based design optimization (RBDO) of the scraper chain is then carried out. Finally, the applicability of the proposed method is verified by the SGZ1000/1400 scraper conveyor.

Combined Influence of Cyclic Loads and Corrosion on the Technical Condition of Metal Structures of Metro Escalators

This article examines the influence of loads, conventionally divided into static and cyclic ones, and of corrosion acting together on the structural elements of metal structures of metro escalators. The dynamics of corrosion processes are determined by the environment, the degree of influence of which, depending on the geographical location and based on seasonality, can vary from non-aggressive to highly aggressive. This, with simultaneous occurrence of deformations (a stressed state is created in the structure), can lead to fatigue failures. The state of the metal structure of the escalator in this case is the most important element, since the failure of almost any of its structural elements means a complete stop of the escalator.The prerequisites for corrosion fatigue for low carbon steels, as the main material in manufacture of metal structures for metro escalators, are also considered.The main objective of the study is to search for criteria for creating an experimental and computational method for determining the residual life of metal structures of metro escalators with a high degree of reliability. Identification and analysis of criteria for assessing the condition of metal structures was carried out by the authors using experimental research and survey methods, that resulted in a conclusion that the degree of degradation of the main characteristics and properties of metal structure elements is determined not only by the number of loading cycles, but also by the duration of exposure to an aggressive environment.

Influence of hot corrosion on thermal fatigue behavior of Ni-based single crystal superalloy: Invisible and accelerated crack

As an important failure model for single crystal materials in service, with the increasing complexity of working environments, the thermal corrosion fatigue failure needs to be studied urgently. In this study, the thermal corrosion fatigue crack initiation and propagation behaviors of an Ni-based single crystal superalloy in both air and hot corrosion environments at 25–900 °C were studied by using a designed precise thermal fatigue test device. The microstructure characteristics and crack composition were analyzed by SEM, TEM and EDS, and the internal stress and recrystallization during thermal fatigue were characterized by EBSD. Moreover, the detailed and comprehensive crack morphology was characterized with different surface treatments. The results showed that the crack morphology was invisible in the hot corrosion environment, which is worthy of being highlighted. The initiation and propagation of thermal fatigue cracks were also accelerated in the hot corrosion environment, which contributed to the sufficient thermal stress, the accelerated material degradation of the inner/outer layers in the crack region, and the rapid forward diffusion of O2 in the inner crack layer. Finally, the influence mechanism of hot corrosion on the thermal fatigue behavior of the Ni-based single crystal superalloy is proposed.

Corrosion fatigue behavior and life prediction of railway axle EA4T alloy steel with artificial indentation

The combined effects of aggressive media and artificial surface indentation on the fatigue behaviours were investigated to evaluate the defect tolerance of high-speed hollow railway EA4T steel axles. Corrosive rotating-bending fatigue tests were performed on both smooth and notched specimens to assess their fatigue strengths and failure mechanisms. Based on the corrosion testing campaign, which mainly included examinations of the microstructure, residual stress, and fatigue crack resistance, material deformation underneath the bottom of indentations triggered corrosion fatigue cracks. The results also showed that the corrosive media was responsible for the decrease in fatigue strength, and notched specimens were more sensitive to 3.5 wt% NaCl solution than to air. The fracture surface indicated that cracks were mainly initiated from the notch of specimens in air, whereas cracks were formed from multiple sources in specimens in the corrosive medium. Finally, a three-parameter Kitagawa-Takahashi diagram was established to correlate the threshold stress range (Δσth) and critical defect size (a) with the corrosion fatigue life (N) in terms of the El-Haddad model, thus providing a scientific reference for the service safe region identification of high-speed railway axles subjected to corrosive environments.

Corrosion fatigue behavior of continuous gradient porous Ti‐15Mo alloy prepared by selective laser melting

AbstractIn this work, porous Ti‐15Mo scaffolds with different porosity gradient structures (uniform gradient structures [U‐BCC], level gradient structures [LG‐BCC], and vertical gradient structures [VG‐BCC]) were fabricated by selective laser melting, and the corrosion fatigue testing in Hank's solution was conducted for the first time. The fatigue strength order, when considering the same fatigue life, follows the sequence of LG‐BCC structure > U‐BCC structure > VG‐BCC structure. Cyclic ratcheting is a prominent factor leading to fatigue failure. The sequence of crack initiation and propagation in the latter stage of corrosion fatigue can be listed as follows: LG‐BCC structure < U‐BCC structure < VG‐BCC structure. During the corrosion fatigue process, the grain refinement occurs, and the deformation twinning is generated, leading to a dissipation of energy and an increase of the fatigue resistance. The corrosive effect of Hank's solution induces the surface roughening of the sample, accelerating crack initiation and propagation.

The Study on Fatigue Crack Growth Rate of 4130X Material under Different Hydrogen Corrosion Conditions.

In this paper, the fatigue crack growth rates of typical pressure vessel material 4130X under different corrosion conditions are investigated, and the effects of corrosion modes and loading frequency on the fatigue crack growth rate of 4130X are discussed. The results show that under the same loading conditions, the pre-corroded crack propagation rate is increased by 1.26 times compared with the uncorroded specimens. The plastic deformation mechanism of the crack tip in air is dominated by phase transformation but the hydrogen introduced by pre-corrosion causes a small number of dislocations at the crack tip. The crack growth rate obtained by corrosion fatigue is four times that of the uncorroded specimen, and the fracture surface shows a strong corrosion effect. The molecular dynamics simulation shows that the hydrogen atoms accumulated at the crack tip make the plastic deformation mechanism dominated by dislocation in the crack propagation process, and the coupling interaction between low frequency and the corrosion environment aggravates the hydrogen embrittlement of the crack tip. In the air condition, the loading frequency has no obvious effect on the crack growth rate: when the frequency decreases from 100 Hz to 0.01 Hz and other conditions remain unchanged, the fatigue crack growth rate increases by 1.5 times. The parameter n in the Paris expression is mainly influenced by frequency. The molecular dynamics simulation shows that low frequency promotes crack tip propagation.

Effect of the surface status on corrosion fatigue of the strained structural materials

Fatigue failure of metal structures during operation is a frequent cause of machinery and equipment failure, and sometimes of human losses. This is especially true for operating conditions in the presence of corrosive environment. Reliable and safe operation of metal products and engineering devices during operation is largely determined by the structure and properties of the used materials and is ensured by optimizing the process operating conditions. The analysis of domestic and foreign literature data has shown that systematic theoretical and experimental studies of the impact of corrosive environment on the resistance to alternating loads on strained metals and alloys are practically absent. In this regard, the issue of identifying the patterns of corrosion and fatigue failure seems to be urgent in order to increase the corrosion fatigue life of plastically strained metals and alloys. This paper analyzes the impact of the status of surface layers of structural metals in a thermally treated and plastically strained state. The factors influencing the metals oxidation susceptibility have been established. During cyclic loading all processes related to vacancies’ concentration and fatigue cracks nucleation are ahead of schedule in the surface layers of metal, and all structural damage is concentrated at the surface, especially in case of corrosion fatigue. Plastic deformation increases both the thermodynamic possibility of oxide formation on the metal surface and the speed of this process. An increase in the active sites density on the surface of the strained metal contributes to the emerging of a large number of oxide nuclei, the growth of which leads to a faster formation of a continuous passivating film than on the surface of an unstrained metal.

Effects of orientation on fatigue behaviors of ZK60 magnesium alloy pre-corroded in PBS

The strong anisotropy of magnesium alloy affects both its corrosion and fatigue performance by orientation, and it is important to investigate the effect of orientations on the two properties for the development of magnesium alloy in the biomedical field. In this paper, through the corrosion experiments and fatigue experiments of corroded specimens, the differences in corrosion resistance and fatigue failure performance of ZK60 magnesium alloy with different orientations were investigated, and the mechanism of these differences was analyzed. In terms of corrosion performance, compared with the RN surface, the RT surface with higher atomic arrangement density has a lower corrosion rate and higher corrosion resistance. In addition, regarding the fatigue performance, the corroded RT-R specimens had the longest fatigue life, followed by the RN-R and RN-N.

Effect of cathodic protection on the corrosion fatigue crack growth behavior and fatigue life of XS-grade shipbuilding steel

Shipbuilding steels are subjected to corrosion fatigue damage phenomena due to conjoint effects of cyclic loading by sea waves and corrosive seawater environment, which often leads to premature failure of ship hull structures. In practice, the impressed current cathodic protection (ICCP) technique is applied to mitigate ship hull corrosion by electrochemically making it cathodic. It is implemented by impressing a direct current to minimize the electrode potential to a predefined protection potential. It is significant to study the effect of ICCP on the corrosion fatigue crack growth rate (CFCGR) behavior and fatigue life assessment of ship hull structures. In this study, CFCGR behavior of high-strength XS-grade shipbuilding steel was investigated in unprotected freely corroding (FC) and protected ICCP (at – 800 mV) conditions using compact-tension specimens at 0.1 Hz frequency in artificial seawater (3.5 wt.% NaCl solution). After crack-closure corrections, it was found that the ICCP-protected specimen (∆KTH = 18 MPa √m) exhibited higher sub-critical or threshold corrosion fatigue crack propagation resistance as compared to the FC specimen (∆KTH = 14 MPa √m). Fractography of the FC specimen revealed the debonding of non-metallic inclusions and formation of micro-pits/secondary cracks as dominant damage mechanisms. ICCP-protected specimen exhibited a signature pattern of parallel secondary cracks and a proportional increase in their density with increasing stress intensity levels during primary crack growth. This fracture morphology indicated the primary-crack branching and further arrest, leading to retarded crack growth rates under ICCP-protection. Fatigue life analysis also confirmed this finding, where the beneficial ICCP-protection effect resulted in at least two times enhancement in fatigue lives from the unprotected FC condition.

Advancing digital healthcare engineering for aging ships and offshore structures: an in-depth review and feasibility analysis

Abstract Aging ships and offshore structures face harsh environmental and operational conditions in remote areas, leading to age-related damages such as corrosion wastage, fatigue cracking, and mechanical denting. These deteriorations, if left unattended, can escalate into catastrophic failures, causing casualties, property damage, and marine pollution. Hence, ensuring the safety and integrity of aging ships and offshore structures is paramount and achievable through innovative healthcare schemes. One such paradigm, digital healthcare engineering (DHE), initially introduced by the final coauthor, aims at providing lifetime healthcare for engineered structures, infrastructure, and individuals (e.g., seafarers) by harnessing advancements in digitalization and communication technologies. The DHE framework comprises five interconnected modules: on-site health parameter monitoring, data transmission to analytics centers, data analytics, simulation and visualization via digital twins, artificial intelligence-driven diagnosis and remedial planning using machine and deep learning, and predictive health condition analysis for future maintenance. This article surveys recent technological advancements pertinent to each DHE module, with a focus on its application to aging ships and offshore structures. The primary objectives include identifying cost-effective and accurate techniques to establish a DHE system for lifetime healthcare of aging ships and offshore structures—a project currently in progress by the authors.

Study on fatigue damage evolution behavior of SLM formed IN 718 alloy

SLM (Selective Laser Melting) Inconel718 alloy has good corrosion resistance, oxidation resistance and fatigue resistance, which is an indispensable and important material in industrial fields such as energy power, aerospace and nuclear power. In this paper, the fatigue damage evolution behavior of SLM Inconel718 alloy under different heat treatment is studied by the MTS fatigue testing machine and DIC (digital image correlation method). The results show that the fatigue evolution of SLM Inconel718 alloy changes slowly in the initial stage of fatigue evolution. When the damage factor reaches the critical value, alloy begins to enter the rapid damage stage. In the steady stage, SLM Inconel718 alloy has small damage accumulation. In the rapid damage stage, the damage degree of SLM Inconel718 alloy increases and the damage accumulates rapidly. The critical damage factor can effectively distinguish these two stages, and the critical damage factor under different heat treatment shows: AT2 > AT1 > AT3.

Gradual change of vibration characteristics of steel truss structure

Abstract In order to investigate the gradual change law of vibration characteristics of steel truss structures under the influence of fatigue loading and uniform corrosion, this study combines the nonlinear cumulative fatigue damage rule, corrosion depth theory, and structural residual performance theory to establish a multi-level gradually changing performance transfer model. The relationship between structural performance and damage behavior is revealed, and a numerical analysis method for the gradual change phenomenon of vibration characteristics of steel truss structures is provided. A two-dimensional finite element analysis framework for gradual changes in vibration characteristics in steel truss structures has been developed and analyzed for a steel truss girder bridge. The results show that the correlation terms of vibration characteristics gradually decay with the increase of operation time, and the degree of decay is related to the severity of fatigue damage or corrosion damage, with the overall trend exhibiting a three-stage change.

Determination of the residual life of the pipe metal under conditions of corrosion fatigue

This paper presents a method for calculating the residual metal life of pipelines with crack-like defects. The results of corrosion and fatigue tests of ordinary grade structural steel VSt3sp, widely used in the oil and gas industry, are presented. The work carried out studies on the effect of cathodic polarization on the cyclic crack resistance of VSt3sp steel under the influence of a carbonate-bicarbonate medium.

Modeling fatigue-assisted pitting in pipeline steel with PCA-XFEM

We present a localized corrosion and cracking damage mechanism (initiation of the pit, propagation of the pit, pit-to-crack transition, and stable cracking) in a pipeline steel under the application of fatigue loading by using sequential coupling of Probabilistic Cellular Automata (PCA) and eXtended Finite Element Method (XFEM). PCA is utilized for describing the localized corrosion damage mechanism. XFEM is used to simulate arbitrary inhomogeneities (cracks, voids, and soft/hard material interfaces (inclusions)) with the help of Level Set Methods (LSM). In the XFEM, the standard finite element is enriched by additional degrees of freedom by invoking the notion of the partition of unity, which alleviates the burden of mesh conformity to the internal boundaries and avoids re-meshing. LSM is used to locate the voids and material interfaces and track the crack propagation location. A localized strain criterion initiates cracks from the pit surface when the pit reaches a critical strain value.The coupling of PCA and XFEM demonstrates good agreement with experimental data regarding stress-assisted pitting corrosion and pit-induced fatigue cracking in the pipeline steel. The study also investigates the effects of boundaries, and initial pit size on fatigue crack initiation and growth. Boundary effects significantly influence crack initiation life and growth behavior, highlighting the importance of considering both defect characteristics and boundary conditions in assessing fatigue performance and structural integrity. Various initial pit sizes and geometric features further affect crack initiation location and transition time. Furthermore, the PCA-XFEM model effectively captures crack behavior in both short and long crack regimes, demonstrating good agreement with experimental data for a selected pit width of 140μm. By incorporating crack driving parameters derived from experiments, the model accurately predicts crack propagation, further enhancing its reliability and predictive capabilities in assessing fatigue crack behavior. Overall, this approach provides valuable insights for predicting the service life and integrity of pipelines subjected to similar loading conditions, thus aiding in designing and maintaining these critical infrastructure components.

Fatigue failure of high precision spindle bearing under extreme service conditions

Four sets of high precision spindle bearings (HPSB) had been in extreme service for 6040 h and 85,000 r/min. The service temperature, wear fatigue form, hardness, residual stress, retained austenite, metamorphic layer and element content of the bearing raceway were analyzed. The surface layer and inner layer of bearing raceway were analyzed by Electron Backscatter Diffraction (EBSD), Focused Ion Beam (FIB) and Transmission Electron Microscopy (TEM). The results show that the service temperature range of the four sets of bearings is from 17.5℃ to 74.7℃. With the increase of rotating speed, the bearing temperature can reach 65℃ at 85,000 r/min. The four sets of bearings have different degrees of wear, including fatigue shedding (FS), wear (W), corrosion (C), peristalsis (P), burn (B) and defect (D). In the extreme speed service, taking the bearing No.2 with the highest temperature as the research object, the maximum and minimum hardness differences of outer ring raceway, inner ring raceway and ball are 423.1 HV, 368.7 HV and 405 HV, respectively. The tangential residual stresses of the outer and inner ring raceways are found to be tensile stresses, which are 31.3 MPa and 110.8 MPa, respectively. The retained austenite in the outer and inner ring raceways of bearings are found to increase abnormally, reaching 36.7 % and 34.7 %, respectively. In addition to the highest Ion (Fe) element, the outer and inner ring raceways of bearings also contain higher Praseodymium (Pr) elements, reaching 35.5 % and 14.5 %, respectively. The maximum thickness of the “white layer” of the outer and inner ring raceways of the bearing is 15 μm and 17 μm, respectively. The surface layer of bearing outer and inner ring raceways contain nanocrystals of 200 nm and 100 nm, respectively. Certain nanocrystalline layer will prolong the service life of bearings. Nanocrystals mainly contain Phosphorus (P) and Copper (Cu) elements. The research findings of this study can provide theoretical and data support for enterprises and scholars in the engineering field.

Microstructure, corrosion behavior, and fatigue resistance of laser powder bed fusion-produced precipitation-hardening martensitic M789 stainless steel

Additive manufacturing has facilitated the fabrication of stainless steel components with intricate designs, providing exceptional strength and corrosion resistance. This advancement, however, poses challenges in accurately predicting fatigue resistance under high-cycle loading, especially when surface features resulting from the printing process and corrosion are overlooked. This study investigates the microstructure of laser powder bed fused Böhler M789 AMPO stainless steel aiming to elucidate its relationship with corrosion resistance and fatigue properties.Through a comprehensive examination of the microstructural features using El-Haddad’s model and extreme value extrapolations, this research reveals the predominant influence of surface roughness, resulting from the printing process, on the fatigue strength of net-shaped specimens. For a stress ratio of 0.1, the estimated fatigue strength ranges between 69 MPa and 162 MPa. Upon mechanically polishing the surface to eliminate the surface roughness effects, the significance of other features is highlighted. Particularly, the effect of corrosion pits, shallow pores and oxides, and internal discontinuities follow in importance.Moreover, this study evaluates the impact of the as-received-oxide layer on corrosion resistance. Upon removal of this layer via surface etching or polishing, an improvement in the stability of the re-formed passive layer was observed. This enhancement is evident in the expanded potential range between the pitting and corrosion potentials, increasing from 0.2 V for the net-shaped surface to 1.05 V for the polished one.This work emphasizes the significance of characterizing microstructural characteristics to predict both fatigue and corrosion resistances. It also highlights potential research areas in additively-manufactured stainless steels.

Low-Frequency Corrosion Fatigue Test Study of Sucker Rods under High-Salinity Well Fluids in Deep CBM Wells

Corrosion fatigue test is the most direct and effective method to study the corrosion fatigue characteristics of sucker rod. At present, the commonly used test method is the high frequency fatigue test, but the working state of sucker rod is typical low-frequency and high-cycle corrosion fatigue, and the test with high frequency will reduce the impact of corrosion. Alloy steel 4330 is widely used in coalbed gas well high strength sucker rod, but the research on its low frequency corrosion fatigue life is relatively few. Therefore, in this paper, the corrosion fatigue test method of axial low-frequency and high-cycle was adopted to study the corrosion fatigue characteristics of 4330 steel sucker rod through the corrosion fatigue test under different typical corrosion media, temperature, and stress levels. The results show that the fatigue life of 4330 sucker rod drops sharply when the Cl− concentration in high salinity well fluid exceeds the threshold value of 155 mg/L. When this threshold is exceeded, the downward trend slows down. It can be seen that the significant factor affecting the corrosion fatigue life of 4330 material is not the concentration of Cl−, but the existence of Cl−. The presence of HCO3− promotes a further decrease in the corrosion fatigue life of the 4330 sucker rod by Cl−. The corrosion fatigue life of 4330 sucker rod decreases with the increase of temperature. When the well fluid temperature is less than 50 °C, the impact is relatively significant. When the well fluid temperature is more than 70 °C, the decline trend of corrosion fatigue life slows down. Based on the fitted S-N curve (stress-fatigue life curve), it is calculated that the fatigue limit of 4330 sucker rod at the stress ratio of 0.6 is 196 MPa in the solution of 10,000 mg/L Cl− at room temperature. These could provide valuable theoretical and technical guidance for design and selection of high-strength sucker rod in high-salinity corrosion well fluid environment.

Effects of exposure in seawater sea-sand concrete pore solution on fatigue performance of carbon FRP bars

The study aims to propose a methodology to predict the fatigue performance of carbon fiber-reinforced polymer (CFRP) bars under the seawater sea-sand concrete (SWSSC) environment. The effects of exposure in SWSSC pore solution on the fatigue damage mechanisms and fatigue performance of CFRP bars are presented. Firstly, the tensile fatigue tests of reference CFRP bars were performed under various stress levels with a constant stress ratio of 0.1. Secondly, the tensile fatigue tests of exposed CFRP bars subject to the simulated SWSSC pore solution were carried out. The tensile failure modes and fatigue damage mechanisms corresponding to different stress levels, were identified using scanning electron microscopy (SEM). Besides, the relationship between fatigue life expectancy and underlying fatigue damage mechanisms was carefully analyzed. Finally, the effective stress level method (ESLM) was proposed to evaluate the residual fatigue life of exposed CFRP bars based on the benchmark S–N curve. Combined with the degradation models (chemical etching/diffusion models) proposed in our previous research, ESLM could bridge corrosion fatigue life prediction of the exposed CFRP bars and the benchmark fatigue data of the non-exposed CFRP reinforcement. The predicted results have good correlations with the experimental data. This method can also provide valuable insight for the corrosion fatigue life prediction of other types of FRP composites.

One-Step PRC Surface Pretreatment for Plating Onto Al Alloys

Faraday will describe our recent work on the development of a one-step electrochemical surface preparation process to prepare aluminum alloys for direct electrodeposition. Coating on aluminum commonly requires extensive surface pretreatment processes prior to deposition, owing to aluminum’s reactive nature and affinity for oxygen, leading to the formation of an oxide film that negatively affects coating adhesion to the substrate. Therefore, preparing the surface is critical to remove any oils or dirt attached to the surface and to remove the native oxide film to increase coating adhesion. Conventionally these issues are addressed by a continuous sequence of twelve (12) pretreatment process steps to prepare the surface for deposition. Such an extensive number of processing steps requires significant capital investment for a new vendor, increases the probability of errors during the process, is time consuming (lower industrial throughput that ties up equipment), and requires large volumes of hazardous chemicals (Hydrofluoric Acid) that are environmentally unfavorable and introduce cost and safety concerns. Therefore, alternative techniques that do not require such extensive pretreatment processing with similar or better performance to conventional methods are desired.Faraday has recently developed a simple environmentally benign pretreatment process utilizing our pulse reverse electrofinishing approach that can dramatically reduce the number of procedures and complexities required to prepare the surface for the direct deposition onto Al alloys. A specific application of interest that requires low-cost, simple fabrication technology for the deposition of wear, erosion, corrosion fatigue resistant coatings onto Al is Neutrino Focusing Horns. Neutrino Focusing Horns, required for research on particle accelerators and storage rings, are commonly made of aluminum. These horns must withstand repetitive thermal and magnetic loadings over millions of pulses in a radiation and corrosive environment and the thickness of the inner conductor is minimized to reduce absorption and scattering of secondary particles in the conductor material. Therefore, protection of the focusing horns from erosion, corrosion and fatigue is of critical importance to assure long time reliability. The most successful coating thus far has been an electroless nickel coating with conventional 12 step pretreatment method. The application of this coating, however, is challenging due to the large size of the horn (4 m x 1 m x 1 m), and industrialization is challenging due to the low part volumes, high capitalization and large number of process steps.This presentation will focus pulse/pulse reverse surface preparation processes being developed by Faraday Technology. It will explore surface pretreatment procedures to simultaneously prepare various Al surfaces such as Al 6061, Al 4043, Al 1100, and Al 5086 and subsequent direct deposition of ZnNi, NiP, or Ni coatings. These coating have since been characterized and compared to baseline electroless NiP coatings for their functional properties. The results of these characterization studies will be discussed in detail.