Surface Treatment Of Alloys Research Articles

A review on modern prosthodontic practice using laser.

Lasers are a very appealing technology in many areas of dentistry because of their minimally invasive nature, quick tissue interaction & response, and ability to heal. Numerous investigations on the possible uses of lasers in dentistry have been carried out since Maiman developed the ruby laser in 1960. Numerous applications such as quick prototyping and computer-aided design, and the study of occlusion in complete denture using three-dimensional laser scanning has been used to develop dentures. Its uses are numerous from fixed prosthodontics to dentinal hypersensitivity treatment to surface treatment of base metal alloys. These days, it even encompasses maxillofacial prosthodontics and dental implantology. Hence, it is of interest to review the use of lasers in clinical prosthodontics.

A novel Mg-Zn-Nd-Zr alloy lumbar interbody fusion cage: An in vitro and in vivo study

Interbody fusion is recognized as the golden standard of surgical intervention for degenerative disc disease (DDD). Interbody fusion cage made of polyetheretherketone (PEEK) is commonly used in lumbar interbody fusion surgery in the treatment of DDD worldwide. However, there are some limitations of PEEK including their bio-inert nature and impediment to host bone integration. This study aimed to evaluate the degradation profile and osteoinductive potential of biodegradable Mg-Zn-Nd-Zr cages with/without micro-arc oxidation (MAO) coatings. The Mg-Zn-Nd-Zr alloy cages, whether coated with MAO or not, demonstrated commendable biocompatibility and biomechanical properties. Immersion and electrochemical tests show better corrosion resistance of MAO coatings in vitro. mRNA sequencing, RT-qPCR and Western blotting revealed that Mg-Zn-Nd-Zr and Mg-Zn-Nd-Zr/MAO had a better effectiveness on osteoinductivity. In vivo evaluations in ovine models over 12 weeks and 24 weeks post-implantation revealed radiological and histological evidence of enhanced bone formation adjacent to the Mg-Zn-Nd-Zr alloy cages compared to PEEK counterparts. Moreover, the MAO-coated cages exhibited a reduced propensity for gas formation. The Mg-Zn-Nd-Zr alloy is as a superior osteoinductive material compared with PEEK, with the MAO coating offering an advantage in mitigating gas production. Nonetheless, further research is warranted to refine the alloy's composition or surface treatments, particularly to address the challenges associated with rapid gas evolution during the early post-implantation period.

Enhanced interfacial bonding strength of hot-pressed titanium Alloy/CFRTP joint via laser ablation and interfacial adhesive

Joining titanium alloy with carbon fiber reinforced thermoplastic (CFRTP) is one of the hot subjects in the automotive and aerospace industries. To improve the joint strength of TC4/CFRTP PA6, this study combined the surface treatment of TC4 alloy, including laser ablation, Silane Coupling Agent (SCA) treatment, and interfacial PA6 adhesive. The results showed that the pretreatment and the laser texturing induced the micro-scale porous and macro-scale groove grid structure, respectively. The superhydrophilicity of the laser texturing as well as amino polar groups induced by SCA treatment promoted the adhesion of the thermoplastic PA6 melt into the microstructure of the TC4 alloy surface. The mechanical interlocking and hydrogen bonding between TC4 alloy and CFRTP PA6 significantly improved the shear strength of the TC4/CFRTP PA6 joint (17.5 MPa). Furthermore, with the incorporation of interfacial PA6 adhesive, the joint strength was further enhanced, and the damage of the TC4/CFRTP PA6 joint was transformed from interfacial to interlaminar CFRTP PA6.

Effect of Surface Nanocrystallization on Wear Behavior of Steels: A Review.

Ferrous alloys, particularly steels, form a specialized class of metallic materials extensively employed in industrial sectors to combat deterioration and failures caused by wear. Despite their commendable mechanical properties, steels are not immune to wear-induced degradation. In this context, surface nanocrystallization (SNC) technologies have carved a distinct niche for themselves by enabling the nanostructuring of the surface layer (with grain sizes < 100 nm). This process enhances overall mechanical properties to a level desirable for wear resistance while preserving the chemical composition. Existing literature has consistently highlighted the efficacy of various SNC methods in improving the wear resistance of ferrous alloys, positioning SNC as a promising tool to extend materials' service life in practical applications. This review provides a comprehensive examination of the SNC techniques employed in surface treatment of ferrous alloys and their impact on wear behavior. We delved into the underlying mechanisms governing wear in SNC-treated Fe-based alloys and concluded with a discussion on current challenges and future perspectives in this evolving field.

Study of the wear resistance of composite coatings modified with h-BN particles on AZ31 magnesium alloy

A low wear resistance is a significant disadvantage of magnesium-based alloys widely used in industry. The results of plasma electrolytic oxidation (PEO) carried out in an aqueous-alkaline phosphate electrolyte with the addition of hexagonal boron nitride (h-BN) powder to obtain coatings with greater wear resistance on the surface of AZ31 magnesium alloy are presented. The PEO method is one of the most promising for surface treatment of magnesium alloys, since oxidation is carried out in alkaline aluminate, silicate or phosphate electrolytes with various functional additives. The addition of nanocrystalline hexagonal h-BN powder in the form of a suspension into the electrolyte volume does not affect the electrical parameters of PEO, and h-BN particles are incorporated into the structure of the formed composite coating, increasing the wear resistance. It is shown that the resulting coatings have a relief typical of PEO with developed morphology and porosity, which change depending on the oxidation time. In this case, the incorporation of h-BN particles into the coating occurs by an inert mechanism, since they do not undergo chemical transformations with the formation of new phases. Composite coatings obtained on the surface of the AZ31 magnesium alloy by the PEO method consist of crystalline phases of MgO and Mg3(PO4)2, regardless of the addition of h-BN particles to the electrolyte. The wear resistance of coatings is 6 – 8 times higher compared to the untreated alloy. The results obtained can be used to produce PEO coatings with increased wear resistance and use them in various sectors of the economy.

Pre-mixed abrasive waterjet peening with post-low stress milling process and the effect of process parameters on the surface integrity of TC11 titanium alloy

Pre-mixed abrasive waterjet peening (PAWJP) is progressively gaining traction in enhancing metal materials’ surface integrity and mechanical behavior. To avoid the disadvantage of PAWJP in the application, a hybrid manufacturing method of pre-mixed abrasive waterjet peening with post-low stress milling (PAWJP-LSM) is proposed and studied experimentally. The principle of PAWJP-LSM was first introduced. Subsequently, the effect of the PAWJP-LSM parameters (i.e., abrasive type, traverse speed, nozzle inlet pressure, and removal amount) on the surface integrity of TC11 titanium alloy and its variation trend were systematically investigated. Results show that the specimen treated with PAWJP using different process parameters formed a PAWJP treatment area with a strengthening depth of 6–275 μm. The minimum surface roughness obtained by PAWJP was 0.727 μm. The maximum surface microhardness significantly increased to approximately 516.3 HV from 402.8 HV, with a maximum micro-hardness rate of 28.2 % and a maximum work hardening depth of 225 μm. The surface compressive residual stress (CRS) induced by PAWJP ranged from −97 to −322 MPa, with a maximum CRS exceeding −890 MPa and a maximum CRS layer thickness of 305 μm. The surface integrity of PAWJP-LSM is further enhanced compared to PAWJP, resulting in a 98.9 % reduction in minimum surface roughness and a 73.7 % reduction compared to the as-received surface roughness. Additionally, PAWJP-LSM exhibited a 98.9 % increase in surface CRS and a 19.4 % increase in maximum CRS. Moreover, the fatigue life was significantly improved by 69.4 %, which was 294.5 % higher than that of the as-received specimen. Nanocrystals with an average size of 27.3 nm were formed in the topmost surface. Overall, the PAWJP-LSM method demonstrated significant potential for engineering applications and exhibited substantial value in the surface treatment of TC11 alloy. This study validated the effectiveness of the proposed PAWJP-LSM method and provided a valuable reference for selecting optimized process parameters.

A Critical Review of Anti-Corrosion Chemical Surface Treatment of Aluminum Alloys Used for Sports Equipment

Aluminum alloys with low-weight property are promising structure materials for sports equipment. Alloying element-rich second-phase particles create the risk of localized corrosion and result in failure of sports equipment. Chromate conversion coatings as conventional and successful surface treatments were employed to provide a thin but compact film against corrosion. However, chromate species were toxic and carcinogenic for human beings and this process has been highly restricted. In this sense, alternative processes such as trivalent chromium conversion coating with low environmental risk require better corrosion-resistant performance compared to chromate conversion coating. In addition, the closed-loop system of the chromate electroplating process has been used in Europe and the United States. This is also a sustainable process for surface treatment of aluminum alloys applied in sports equipment. The present paper aims to summarize the methods and types of different aluminum alloy surface treatments and compiles the effects of various surface treatments on the corrosion resistance of aluminum alloys. The eco-friendly application of aluminum alloys in the field of sports equipment may be facilitated in the future.

Effect of alloy composition on the 45 steel microstructure and properties of scanning electron beam surface alloying

In order to improve the surface properties of 45 steel, the effects of different scanning electron beam treatments on the surface properties of 45 steel were studied. The research results indicate that after scanning electron beam surface alloying (SEBSA) treatment, in addition to forming needle like martensite, carbides (tungsten carbide and molybdenum carbide) also exist in the alloying zone of the strengthening layer, moreover, the grains become finer. After scanning electron beam alloying treatment, the surface hardness reached 1250HV, which is 5-6 times the substrate. Compared with the wear loss of the matrix, the wear resistance of the sample after SEBSA treatment increased by nearly six times.

Effect of passivation and surface treatment of a laser powder bed fusion biomedical titanium alloy on corrosion resistance and protein adsorption

The biomedical titanium alloy Ti6Al4V has excellent corrosion resistance and biocompatibility and is, therefore, widely used in orthopedic and orthodontic implants. Biomedical implants are increasingly fabricated by additive manufacturing, such as laser powder bed fusion (LPBF). These manufacturing protocols often include sandblasting, surface finish, and passivation. This study aims to investigate the effect of different surface finishes and the commonly used ASTM F86–13 nitric acid passivation for LPBF Ti6Al4V on its corrosion resistance, metal release, and surface changes in benign (bovine serum albumin in a pH 7.4 buffer) and harsh (hydrochloric acid at pH 1.5) solutions using various electrochemical and spectroscopic techniques. Electrochemical, solution and surface analysis showed an insignificant effect of passivation. Smooth surfaces exhibited a slightly better corrosion resistance than rough surfaces due to a 10–20 % smaller true surface area and lower protein adsorption. Implanted ceramic beads from the sandblasting procedure remained on the surface even after the mirror-polishing and passivation procedures.

Surface Modification of Ti-Nb Alloy in Alkaline Solution to Enhance Bioactivity

Titanium alloys, especially titanium-niobium alloy have been reported as a potential biomaterial with good biocompatibility and non-toxicity. However, there is a lack of studies in alkaline surface treatment of new beta titanium alloy fabricated by vacuum arc melting (VAM) and powder metallurgy (PM) technique with high addition of niobium percentage. The purpose of this research was to examine the feasibility of surface modification on new beta Ti-40wt% Nb alloy in sodium hydroxide solution in order to form bioactive alkaline titanate layer. The characterization involved in this study is X-ray diffraction analysis (XRD), scanning electron microscope (SEM), microhardness, density measurement and optical microscope (OM). Development of amorphous alkaline titanate layer consisted of titanium hydrate, sodium titanate and oxide mixture of titanium oxide, niobium, niobium oxide were revealed by XRD. SEM shows titanate hydrogel layer form on Ti alloy PM thicker than on Ti alloy VAM. Microhardness and density measurement for Ti alloy VAM is greater than Ti alloy PM. OM shows porous surface on Ti alloy PM compare to VAM. This research suggests that the formation of sodium titanate layer on the surface of Ti-Nb alloy enhance bioactivity with better osteointegration and present higher formation of apatite which is crucial for the desired biomedical implant.

Construction and growth of black PEO coatings on aluminum alloys for enhanced wear and impact resistance

Black coatings with superior optical properties have attracted considerable attention for the surface treatment of aluminum alloys. This study focuses on the development of black coatings with superior mechanical properties on 6061Al alloy using plasma electrolyte oxidation (PEO) technique. Two different electrolytes are designed, and the effects of different electrolyte components on the microstructure, composition, growth mode, and mechanical properties of black coatings are investigated. The results show that the inward-outward growth behavior and mechanical properties of coatings are strongly influenced by the deposition originating from the electrolyte. The deposition of P– and V–containing coatings in the mixed electrolyte composed of phosphate and metavanadate proceeds easily, forming outer deposition layers with loose structures. This makes the growth of coatings largely dependent on the mode of outward growth and decreases the adhesion strength. Conversely, in the mixed electrolyte of phosphate and dichromate, the deposition of species from the electrolyte is difficult, resulting in the initial growth of coatings that relies on the oxidation of the substrate. Such a growth mode is characterized by inward growth, which endows coatings with excellent wear and impact resistance. Furthermore, the coloring mechanism is discussed, and it is concluded that the doping of vanadium (V) or chromium (Cr), especially Cr, into alumina significantly contributes to the black appearance of the coatings.

A Critical Review on Fiber Metal Laminates (FML): From Manufacturing to Sustainable Processing

Composite materials such as Fiber Metal Laminates (FMLs) have attracted the interest of the aerospace and automotive industries due to their high strength to weight ratio, but to use them as structures it is necessary to master the manufacturing and wiring techniques of these materials. Therefore, this paper aims to address and summarize the drilling and milling processes in FMLs based on a literature review of papers published from 2000 to 2023. Parameters used in multi-material manufacturing and machining such as drilling and milling, tool geometry, tool coating, lubricants and coolants published by researchers were analyzed, compared and discussed. Machining process parameters related to sustainability were also analyzed. A SWOT analysis was carried out and discussed to identify opportunities for improvement in the machining process. There are opportunities to develop the surface treatment of aluminum alloys, such as testing other combinations than those already used, testing non-traditional surface treatments and manufacturing modes, and developing sustainable techniques during the FML manufacturing process. In the area of tooling, the opportunities are mainly related to coatings for tools and changing machining parameters to achieve an optimum finished part. Finally, to improve the sustainability of the process, it is necessary to test coated drills under cryogenic conditions to reduce the use of lubricants during the machining process.

Prospecting for the Surface Treatment of a Nickel-Aluminium Bronze Alloy Using the TIG Process

In this study the TIG process was used to perform the surface treatment of Nickel-Aluminium Bronze alloy (C63280), the main material used in the industry for the manufacture of naval propellers. The process was applied in specimens obtained from a propeller blade at different current pulsation frequencies (2, 5, 6, 12 Hz and 30 kHz) and without pulsation. The treatments were submitted to microstructural and microhardness analysis, and the results were compared to the material without any treatment. As for the microstructural aspect, all treatments resulted in grain refining, as this aspect is more accentuated for the frequency of 6Hz. The analysis also revealed a lower volume of the α phase in all treatments, which was evidenced upon investigation of the microhardness, with dispersion of the β phase in all samples and the k phase in some samples. The results show a greater uniformity in the microhardness in the treated zone due to grain refining. However, when comparing the average microhardness with the microhardness of the reference material, a significant increase of the microhardness was reached only at the frequency of 6Hz.

Comparative assessment of TiN thin films created by plasma deposition technique on the surface features of NiCr alloys for dental applications

Introduction: Surface treatment is an important technique to increase adhesion between implants and bones, improving its mechanical characteristics and consequently the patient’s comfort. Objectives: Ni-Cr alloys were the object of study in this work, with the purpose of analyzing and evaluating the effect of thin films deposition of titanium nitride via plasma, on its surface and comparing with cathodic cage (CC) and hollow cathode (HC) methods, for dental applications. Methods: Eighteen samples were prepared and the experiment was conducted in two steps: the pre-sputtering (1h, 350 °C, gases: Ar and H) and sputtering (4h, 450 °C, gases: Ar, Ni, and H). To characterize and compare the samples with those of reference, the Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Vickers Microhardness and wettability tests were used. Results: The results presented by SEM showed that during the surface treatment using CC, voids were formed, and using HC, the samples showed a more homogenous behavior. In microhardness tests, using a 25gf load, it was possible to observe that the HC method allowed an increase of 87% when compared to the reference and treated samples. Significance: Lastly, it can be concluded that both methods are suitable for Ni-Cr alloy surface treatment, and the HC technique, a method already used by dental professionals, presents better results due to the formation of a thicker film layer.

Tribological Properties of Ti6Al4V Alloy Composite Texture Fabricated by Ultrasonic Strengthening Grinding and Laser Processing

The Ti6Al4V alloy has been widely used in aerospace equipment and medical devices. However, the poor wear resistance of the Ti6Al4V alloy hinders its further engineering application. In this study, the ultrasonic strengthening grinding process (USGP) and laser texturing process were employed to enhance the wear resistance of Ti6Al4V alloy. The frictional behavior of all samples was determined via a ball-on-disc friction and wear tester under dry conditions. The worn surface morphology, cross-sectional hardness, surface roughness, and microstructure were analyzed. The results demonstrated that the USGP induced high hardness, high dislocation density, and grain refinement, as well as improvements in the wear resistance of Ti6Al4V. Moreover, laser texture could enhance the capacity to capture wear debris and reduce wear probability. When combining the USGP and laser texturing process for the surface treatment of Ti6Al4V alloy, the lowest and most stable friction coefficients were obtained, as well as the best wear resistance. Compared to the polished sample, the steady stage friction coefficient of the sample treated by USGP and laser texturing process was remarkably decreased by 58%. This work demonstrates that combining the USGP and laser texturing process could be a promising solution for improving the wear resistance properties of Ti6Al4V alloy, which makes it more suitable for various engineering applications.

PHYSICO-CHEMICAL FOUNDATIONS OF INNOVATIVE TECHNOLOGIES IN THE FIELD OF PHOTOCATALYSIS

An analysis of the physical and chemical foundations of the synthesis of photocatalytic materials on metal platforms was carried out in terms of the restructuring of the country's industrial production according to the new Industry 4.0 paradigm. Possible ways to improve the functional properties of such materials are determined using titanium dioxide as the most effective and accessible material for creating photocatalysts by doping with non-metal and metal compounds or creating composites and non-stoichiometric oxides as an example. A variant way of creating heterooxide composites by inversion of the elements of the structure-forming matrices and the strengthening phase is proposed. A detailed analysis of the problems arising during the surface treatment of high-alloy valve metal alloys by electrochemical technologies is given, and directions for solving such problems due to the homogenization of the surface layers of the processed materials are determined. A technological scheme for the implementation of such a methodology for variable scenarios using plasma-electrolyte oxidation is proposed. The difference in the electrochemical characteristics of heterooxide composites depending on the nature of the dopants was established, which is fully consistent with the nature of the latter.

Fabrication of electrocatalytic anode by surface treatment of 4J40 INVAR alloy for feasible water splitting

A binder-free, self-supporting and substrate-rejuvenating electrocatalytic electrode based on nonnoble elements is widely acknowledged as the most potential candidate for feasible water splitting. Through the consecutive surface treatment including Fe-leaching in a simple KSCN solution, anodic polarization and chronopotentiometric aging in KOH solution, a commercially available 4J40 INVAR alloy was adopted in this work to fabricate an anode for oxygen evolution in alkaline media. Featuring all above advantages over most state-of-the-art OER electrocatalysts, the 4J40 electrode after being stabilized by CP-aging needs an overpotential of only 241 mV to achieve the current density of 10 mA cm−2 in 1 M KOH, in addition to its stability tested at the lower and higher current densities, respectively. The controlling OER mechanisms were discussed accordingly, with the Fe-doped nickel-based oxyhydroxide and the nickel peroxide being considered correspondingly as the main OER-enhancing species before and after CP-aging.

Effect of heating VK and TK group hard alloys in various media on surface quality

The studies carried out to explore the modifying effect on the surface of a hard alloy, surface alloying and thermochemical treatment of metal, thermal diffusion saturation, vacuum ion-plasma deposition demonstrated changes in surface roughness and performance. This paper used roughness to evaluate the behavior of various hard alloy groups when heated in various media. The samples were 5× 5× 35 mm bars and 15.8 ×15.8 mm tetrahedral plates made of VK8 and T14K8 hard alloys. Surface roughness parameters were measured on the profilometer implementing the contact (probe) method. Roughness values obtained were analyzed in the Microsoft Excel system based on an integral percentage and histograms were constructed. The effect of the heating medium on the surface roughness was studied both on bars and plates (with and without holes) using the saturating element/buffer substance (50–100 % BaCl2) melt. K4(Fe(CN)6 potassium ferrocyanide and Na2B4O7 borax were used as a saturating element (25 %). Microhardness and cutting wear were determined directly on the products (after determining the heating media effect on roughness). The heating of VK8 and T14K8 hard alloys in various media increases roughness and reduces cutting wear up to 2 times. The structure of initial materials before and after heating in various melts was studied using the JCM-6000 scanning electron microscope (Jeol Ltd., Japan) at a magnification of 1000–3000×. Plates in their initial state and after heating in various melts were subjected to resistance tests on the 1A616 screw-cutting lathe by face turning of an axle billet made of OS steel (similar in structure and properties to St45) 210 ×1650 mm in size of continuously cast metal (GOST 4728-2010). X-ray diffraction analysis of the VK8 hard alloy after heating in various media demonstrated the absence of changes in the phase composition. Along with this, there was a slight change in the carbide phase fine structure parameters of the alloy, namely a slight increase in micro-stresses with a simultaneous decrease in mosaic blocks.

Laser Surface Alloying of Sintered Stainless Steel.

A characteristic feature of sintered stainless steel (SSS) is its porosity. Porosity results in a lower density of steel, making attractive components for producing lightweight structures and materials used in industry (e.g., the automotive industry or aerospace). Scientists also observe that porosity adversely affects steel’s properties, especially its strength properties. One of the proposals for improving the discussed properties is the use of surface treatment of sintered stainless steels, e.g., with the use of concentrated energy sources such as plasma beams or laser beams. However, this proposal is an incidental subject of research, which is not justified from the point of view of the obtained research results presented by a few research groups. In this study, the surface modification (surface treatment) of sintered stainless steel was presented. The authors proposed the use of two surface treatments in order to compare them and obtain the best results. The first treatment was the deposit of Cr3C2–NiCr coatings on SSS surfaces using the atmospheric plasma spraying (APS) method. The second treatment was to create surface layers on SSSs by laser alloying the surface with a CO2 laser. Due to high precision and ease of automation, the most common methods in surface alloying treatment are laser technologies. This research’s main aim was to analyze the microstructure and strength properties of the SSS surface layer. The research confirms that applying the Cr3C2–NiCr coating and modifying the surface layer through the laser alloying method improves the mechanical properties of SSSs.

Low-cycle fatigue behavior and surface treatment of a twinning-induced plasticity high-entropy alloy

The low-cycle fatigue life and cyclic deformation behavior of a metastable high-entropy alloy were investigated in this study. Additionally, the effects of the ultrasonic nanocrystal surface modification (UNSM) process on tensile properties and fatigue life were evaluated. Heat treatment following the cold rolling of Fe40Mn40Co10Cr10 alloy plates resulted in the formation of a coarse grain size of 46.7 ± 19.6 μm. Additional mechanical twins were activated during tensile testing compared to the equiatomic CoCrFeMnNi alloy, leading to increased elongation. However, mechanical twins in cyclic loads appear only at high strain amplitudes. Therefore, similar to the CoCrFeMnNi alloy, the slip of dislocations was the dominant cyclic deformation mechanism and the fatigue life of the alloys were comparable. The UNSM process formed a deformed gradient layer with a thickness of approximately 200 μm on the alloy surface. In addition to mechanical twins and low-angle grain boundaries, ultrafine grains with diameters as small as 200 ± 120 nm are detectable in this layer. Although this surface treatment successfully increased the yield strength by more than 70%, fatigue crack initiation was accelerated and fatigue crack growth resistance was degraded.