Surface Mechanical Properties Research Articles

Experimental investigation on the problems in the achievement of super-smooth surface of cemented carbide WC-Co through diamond turning

The processing of cemented carbide (WC-Co) with mechanical methods has become problematic in the production of functional parts and molds due to the great brittleness and hardness. The application of ductile-regime machining to process the WC-Co has been attempted, but the outcomes are not satisfactory. To better understand the processing of WC-Co, the Vickers indentation, nanoindentation, single point diamond turning, and taper cutting experiments are carried out by referring to the empirical parameters, instrument options, and published works. Firstly, the effectiveness of the reported models in predicting the critical uncut chip thickness of brittle-ductile transition of WC-Co are verified and discussed in terms of the experimental observations. Then the impact of diamond turning on the morphologies and mechanical properties of the machined surface are examined. After that, the defects that affect the surface quality of WC-Co are analyzed. The results indicate that the deterioration of surface quality is dominantly decided by the breakage of WC grain. The grain breakage induced defects and further observations of taper cutting on the WC-Co reveal that the critical uncut chip thickness (40–50 nm) required to produce a super-smooth surface is much smaller than the depths predicted by the reported models of brittle-ductile transition (0.674–1.008 μm). Such difference may be derived from the improper use of fracture toughness and application of models that treat the workpiece material as a continuous and evenly distributed medium. Finally, a modified diamond turning process is conducted to verify the effectiveness of the analysis.

Laser powder bed fused 304L steel shot-peened with various ceramic shot sizes: Surface/subsurface characteristics, tensile behavior, and fatigue behavior

Shot peening is an efficient post-processing technique for eliminating surface manufacturing defects, inducing compressive residual stress, and improving the mechanical properties of laser powder bed fused (L-PBFed) metallic materials. With a series of microstructural characterizations, this work comprehensively evaluated the influence of ceramic shot size on the surface characteristics, subsurface characteristics, and mechanical properties, especially fatigue performance, of L-PBF manufactured 304L austenitic stainless steel (SS). The mechanical testing process was in situ observed using an infrared thermal camera, and the tensile-fractured and fatigue-fractured microstructures were systematically examined, aiming to explore the life improvement mechanisms caused by different ceramic shot sizes. The results revealed that when compared to small-sized AZB 100 shots, the large-sized AZB 300 shots could result in higher surface roughness, larger thickness reduction, more apparent surface gradient structure, higher strength, and longer fatigue lifetimes. The strength improvement could be associated with the size reduction of L-PBF induced subsurface defects, the grain refinement at the surface layer, and the α'-martensitic transformation during tensile deformation. The life improvement could be primarily attributed to the subsurface defect strengthening, which resulted in the fatigue crack initiation transition from subsurface defects to surface defects. During the fatigue process, the energy dissipation originating from the core materials dominated the thermal equilibrium temperature, whereas the density of micro-defects (crystalline defects) at the surface layer dominated the crack tip temperature. These findings provide a basic understanding of how to advance the shot peening process for L-PBFed materials.

Extraction and Characterization of Natural CASCABELA Thevetia Bast Fibers: A Potential Candidate as Reinforcement in Epoxy Composites

ABSTRACT The aim of this study is to explore the potential of CASCABELA thevetia (CT) bast fibers as reinforcement in polymer composites. For this purpose, the extracted fibers were chemically treated with various chemicals such as sodium hydroxide, potassium permanganate, sodium chlorite, and benzoyl chloride. After surface modifications, its physical and mechanical properties, chemical composition, and structure were studied. The X-ray diffraction (XRD) results revealed an increase in crystallinity index of the fibers as compared to untreated fibers with benzoyl chloride treated fibers showing the optimum result which agrees with the results obtained in the mechanical tests. Composites were fabricated by taking various wt.% of benzoyl chloride treated CT fibers in an epoxy matrix (i.e. 5, 10, 15, 20, 25, and 30 wt%) and their mechanical and wettability tests were carried out. It was observed that composites with 20 wt% of fiber loading show the highest mechanical properties (52.79 MPa tensile strength, 2.45 GPa Young’s modulus, 71.72 MPa flexural strength). All the fabricated composites showed contact angle less than 90°, which is associated with composite hydrophilic surface properties. These composites can be utilized in lightweight structural material and in automobile industries owing to its better properties.

Voxel-based variable width continuous spiral path planning for 3D printing

Discontinuous printing paths in 3D printing lead to wasted time in fabricating products. This paper proposes a voxel-based continuous spiral path planning algorithm for 3D printing parts with less time consumption. Interestingly, we found our method can also improve the surface qualities and mechanical properties of the printed parts. The proposed path planning strategy in this paper is based on voxels which is different from traditional path planning strategies in literature. Firstly, our proposed algorithm determines the voxel size by considering the printable width of the printer nozzle. It then generates discrete elements by voxelizing the model and creates spirals and line segments by restricting the print direction of the connectable discrete elements. Next, the algorithm employs the Euler circuit to generate continuous sub-paths for the spirals and line segments. It utilizes the depth-first traversal algorithm to traverse and open the continuous sub-paths, resulting in printable continuous paths. To maintain surface accuracy for complex models, contour lines are introduced on the model's exterior and connected internally to ensure global path continuity. Lastly, the algorithm controls the path width in different directions by adjusting the extrusion rate of the printhead, preventing path overlap. Experimental results demonstrate that the proposed algorithm outperforms traditional path planning algorithms and the Connected Fermat spirals algorithm. The proposed strategy effectively mitigates the negative effects of path discontinuity, reduces printing time, and improves printed accuracy, and mechanical properties.

Controlled modulation of coating morphology, mechanical properties and anti-tarnishing response of nanocrystalline Au-Cu alloy coatings electrodeposited from a thiourea (TU)-based non-toxic cyanide-free bath: Effect of current density variation

In the present work, Au-Cu alloy coatings are prepared by pulse galvanostatic electrodeposition from a novel thiourea (TU)-based bath by varying the current density from 5 to 25 mA/cm2. The effect of the applied current density on the surface morphology, mechanical properties, and anti-tarnishing performance of the developed Au-Cu coatings is investigated. Linear sweep voltammetry (LSV) experiments from different bath compositions are carried out to explore the electroanalytical behaviour of Au and Cu in the system. The SEM and EDS investigations show a wide variation in the surface morphology and Cu content of the deposited coatings as the applied current density changes from 5 to 25 mA/cm2. As the current density increases, the hardness of the coatings escalates from 173 to 279 VHN. The electrochemical impedance spectroscopy (EIS) studies suggest that the severity of tarnishing decreases with the increase in the current density.

Fatigue strength of hot-dip galvanized additively manufactured steel

This study investigated the fatigue resistance of additively manufactured steel plates with galvanized surfaces. Therefore, the effects of hot-dip galvanization (HDG) on the surface characteristics, mechanical properties, and fatigue resistance of the manufactured samples were investigated. This research involved measurements of the surface roughness and waviness before and after the HDG process to assess the impact of the zinc layer. Statistical analysis revealed no significant difference in the distribution of surface roughness; however, microscopic examination revealed sharper notches owing to the vertical growth of the zinc layer.Quasi-static tension tests demonstrated that HDG has a minimal influence on the yield strength, provided that the load transfer contribution of the soft zinc layer is excluded. Nonetheless, the mean elongation at fracture was slightly reduced in the HDG samples. Remarkably, a significant effect on fatigue resistance was observed with a detail category of 80 and an inverse slope of m = 3. This fatigue resistance aligned closely with that of the as-welded samples under high stress ranges while demonstrating a lower resistance under smaller stress ranges.

Preparation of GO‐SiO2 three‐dimensional point‐plane nanomaterials and enhancement of epoxy resin mechanical property

AbstractIn this research, mercapto‐anchoring graphene oxide (GO) and epoxy‐anchoring SiO2 nanoparticles (NPs) were assembled by mercapto‐epoxy click chemistry to form three‐dimensional (3D) point‐plane structure nanomaterials (GO‐SiO2), and epoxy resin (EP) composites were prepared using the auxiliary thermal blending method. The relationships among surface interfacial interaction, dispersion, and mechanical properties of composites were systematically investigated. The Research finding shows that SiO2 NPs covalently bonding with GO increases interface compatibility and dispersion, which explains epoxy composite strengthening. Compared to epoxy resin, 0.1 wt% GO‐SiO2/EP composite has 38.65%, 36.15%, 44.64%, and 61.61% higher tensile strength, flexural strength, flexural modulus, and impact strengths. The enhancement mechanism of GO‐SiO2 toward EP was analyzed.

Investigation of thermal annealing on the characteristics of ScxAl1−xN thin films

Good temperature stability is essential for radio-frequency (RF) devices working at high frequencies. AlN and Sc doped AlN (ScxAl1−xN) are widely used as piezoelectric thin films for their excellent performance, but the temperature characteristics of these two materials could be more precise. In this work, the effect of high-temperature thermal annealing on the characteristics of ScxAl1−xN thin films was investigated. ScxAl1−xN thin films with different Sc compositions were deposited and then annealed in different atmospheres at various temperatures. It was found that ScxAl1−xN thin films could maintain good temperature stability below 900 °C in vacuum or air, and AlN can even maintain up to 1300 °C under vacuum. When the annealing temperature exceeded 900 °C, the films’ crystallinity and lattice would appear to have apparent changes. Moreover, the introduction of oxygen at elevated temperatures could impair the surface morphologies and mechanical properties of the ScxAl1−xN thin films. The results revealed that the increased Sc composition decreased the temperature stability of the ScxAl1−xN thin films, and AlN was proved to have better temperature stability than the other two thin films. This work establishes a research foundation for utilizing ScxAl1−xN thin films in high-temperature applications.

Surface Characterization, Mechanical Properties, and Corrosion Behavior of Zn-Ni Alloy Coated Steel Using Electroplating-Hot-Dip Galvanizing

In this study, the processing of zinc-nickel alloys with an electroplated nickel layer as the first layer followed by hot-dip galvanizing on plain carbon steel (St37) is investigated. The effect of the nickel layer and the effect of the immersion time on the alloy layers of the coating obtained by this method are studied. In addition, some properties of the obtained coating, such as the overall thickness, hardness, surface uniformity, coating adhesion strength, and corrosion resistance, were investigated using the optical microscope, scanning electron microscopy, energy dispersive x-ray spectrometer analysis, and potentiostat. The results show that the 16-min immersion time is the optimum galvanizing time at which an alloy with a nickel content of 0.11 wt% is formed and that the overall thickness of the galvanized sheet, especially the alloy layers, decreases compared to the pure zinc sheet. In addition, a more ductile, corrosion-resistant, and smoother surface is obtained.

Durable and impact-resistant thermoset polymers for the extreme environment of low Earth orbit

Polymers degrade rapidly in low-Earth orbit (LEO) due to extreme thermal cycling, solar radiation, micrometeoroid and orbital micro-debris impact, and the synergistic erosive effects of atomic oxygen (AO) with UV radiation. In this work, we investigate the synergistic effect of (AO+UV)-induced erosion and high-velocity impact damage on a tough thermoset, polydicyclopentadiene (pDCPD), via erosion yield measurements after a long-term LEO exposure in the ram orientation aboard the International Space Station (ISS) followed by ground-based hypervelocity impact tests. The incorporation of SiO2 nanoparticles reduces the AO-erosion rate by an order of magnitude, while also mitigating the associated degradation of surface mechanical properties. Moreover, the resistance of pDCPD to AO-erosion increases with crosslink density. Hypervelocity impact tests using sub-millimeter laser-driven flyer plates launched at 4.5 km s−1 reveal that pDCPD has higher impact resistance than epoxies with comparable erosion resistance. Interestingly, both epoxy and pDCPD exhibit a statistically insignificant change in impact resistance following surface AO-erosion during direct exposure to space vehicle ram conditions (7.8 km s−1) in LEO.

Biodegradable zinc‐based materials with a polymer coating designed for biomedical applications

AbstractOver the last decades, biodegradable metals have gained popularity for biomedical applications due to their ability to assist in tissue healing. These materials degrade in vivo, while the corrosion products formed are either absorbed or excreted by the body, and no further surgical intervention is required for removal. Intensive research has been carried out mainly on degradable biomaterials based on Mg and Fe. In recent years, zinc‐based degradable biomaterials have been explored by the biomedical community for their intrinsic physiological relevance, desirable biocompatibility, intermediate degradation rate, tuneable mechanical properties and pro‐regeneration properties. Since pure Zn does not exhibit sufficient mechanical properties for orthopedic applications, various Zn alloys with better properties are being developed. In this work, the combined effect of minor Fe addition to Zn and a polyethyleneglycol (PEG) coating on the surface morphology, degradation, cytotoxicity and mechanical properties of Zn‐based materials was studied. There are several studies regarding the influence of the production of Zn alloys, but the effect of polymer coating on the properties of Zn‐based materials has not been reported yet. A positive effect of Fe addition and polymer coating on the degradation rate and mechanical properties was observed. However, a reduction in biocompatibility was also detected.

Selective laser sintering additive manufacturing of solid oral dosage form: Effect of laser power and hatch spacing on the physico-technical behaviour of sintered printlets

Selective laser sintering is a laser-based powder bed fusion 3D printing technique in which, the laser parameters plays a vital role in the fusion of polymeric powder particles and the behavior of the final printed object. Hence, the objective of the current study was to investigate the impact of laser power and hatch spacing on the fusion of particles, followed by their physicochemical and mechanical behavior investigations of the final sintered object made with dapsone and poly (1-vinylpyrrolidone-co-vinyl acetate) as a model drug and polymer, respectively. An increase in laser power and a decrease in hatch spacing improved particle fusion, resulting in smoother surface, increased density, and better mechanical properties. Interestingly, there was a loss of drug crystallinity was experienced in respect to varied laser parameters, highlighting the potential of laser-based powder bed fusion technique in developing amorphous solid dispersions. Despite extensive laser parameters, drug entrapment efficiency was found to be greater than 90 % for all sintered batches. No notable differences were observed in the dissolution behavior of all performed samples although it was anticipated to achieve as there was differences witnessed in porosity and disintegration time. Finally, the oral pharmacokinetics study revealed the comparable performance of the sintered dosage form with the tablet prepared with conventional direct compression techniques. Overall, these findings demonstrate that with varying laser parameters, various properties of the final sintered object can be manipulated which further showed the flexibility of this 3D printing technique to fabricate dosage form with a more personalized and customized needs.

Effect of molecular and atomic layer deposition thickness in zinc oxide hybrid films on surface cracks and mechanical properties of ultra-high molecular weight polyethylene

The integration of molecular/atomic layer deposition (MLD/ALD) techniques offers a versatile platform for the fabrication of functional organic-inorganic hybrid thin-film structures. In this study, we utilized a hybrid thin-film approach comprising of a zinc oxide (ZnO) ALD layer and a diethylzinc (DEZ) + hydroquinone (HQ) MLD layer to enhance the surface quality and mechanical properties. The objective of this research was to investigate the changes in surface crack pattern and mechanical properties of the hybrid thin films by varying the composition and number of MLD/ALD layers while maintaining a fixed MLD/ALD ratio of 1:5. The hybrid films were synthesized using the [(DEZ + HQ) m + (DEZ + H2O) 5 m]n structure, where the value of mxn was fixed at 200, and the value of m was varied between 5, 10, 20, 100, and 200. The hybrid films were designated as Hm, and their surface morphology was observed by scanning electron microscopy to identify the presence of cracks. The mechanical properties of the films were evaluated by measuring the hardness and elastic modulus of an ALD-coated ultra-high molecular weight polyethylene using nano-indentation examinations, and the films' behavior in the wear environment was studied through micro-scratch testing. The results indicate that H5 and H10 hybrid films exhibited no surface cracks, while serious surface cracks were observed in H20 and H100 films. X-ray diffraction analysis showed that structural changes occurred in the hybrid films, and it was speculated that this was related to surface failure. The hardness and elastic modulus values increased with an increase in the m value and showed significant differences between hybrid films. This study demonstrated that the MLD/ALD-based hybrid thin-film approach is an effective means of enhancing surface quality and mechanical properties. The findings of this study have significant implications for the development of advanced materials and coatings for various industrial applications.

Effect of pre-corrosion on the cavitation erosion performance of two aluminum bronzes in 3.5% NaCl solution

The cavitation erosion (CE) behaviors of two aluminum bronzes after pre-corrosion in 3.5% NaCl solution were studied. Results indicated that the CE rate was increased by a factor of 82% for the nickel aluminum bronze (NAB) and 26.73% for the manganese aluminum bronze (MAB) after 30 days’ pre-immersion, compared with the results of the corresponding fresh sample without pre-corrosion. Mechanical impact was dominantly responsible for the CE damage of the pre-corroded samples. Pre-corrosion increased the E/T (the contribution of pure erosion to the CE-corrosion damage) value from 42.66% to 65.20% for the NAB and from 72.46% to 80.13% for the MAB. After pre-immersion, pits appeared at the eutectoid microstructure in the NAB and the network-shaped β phases in the MAB because of selective phase corrosion. This increased the surface roughness and weakened the surface mechanical property. Therefore, large and deep cavities and remarkable material loss were created due to the collapse of eutectoid microstructure in the NAB and the detachment of κ phases and brittle fracture of β phases in the MAB. The grievous CE damage of the MAB samples was highly attributed to the inferior mechanical property. In contrast, pre-corrosion had a much greater influence on the CE behavior of the NAB, because the CE resistance was remarkably deteriorated as a result of the corrosion damage at the eutectoid microstructure.

Fabrication and optimization of multilayered composite scaffold made of sulfated alginate-based nanofiber/decellularized Wharton's jelly ECM for tympanic membrane tissue engineering

In this study, we fabricated a novel multilayer polyvinyl alcohol (PVA)/alginate sulfate (ALG-S) nanofiber/decellularized Wharton's Jelly ECM (d-ECM) composite for tympanic membrane perforations (TMPs) tissue engineering (TE). Initially, electrospun PVA/ALG-S scaffolds with different blend ratios were fabricated. The influence of ALG-S ratio on surface morphology, mechanical, physical and biological properties of the nanofibers was studied. Secondly, 3-layer composites were developed as a combination of PVA/ALG-S nanofibers and d-ECM to take synergic advantages of electrospun mats and d-ECM. As part of the evaluation of the effects of d-ECM incorporation, the composite's mechanical properties, in vitro degradation, swelling ratio, and biological activities were assessed. The MTT assay showed that PVA/ALG-S nanofibers with 50:50 ratio provided a more desirable environment to support cell growth. A composite containing 25 mg/cm2 d-ECM was determined as the optimal composite through MTT assay, and this composite was used for animal studies inducing TMP regeneration. According to the in vivo studies, the optimal composite not only stimulated the healing of TMPs but also shortened the healing period. These results suggest that a multilayer nanofiber/hydrogel composite could be a potential platform for regenerating TMPs.

Performance degradation mechanism of γ-ray irradiated sol-gel silica film

γ-ray radiation effect on sol-gel silica films was investigated at different absorbed doses ranging from 10 kGy to 1000 kGy. The defect and microstructure evolutions of silica films were analyzed to understand the performance degradation behavior and mechanism of the γ-ray irradiated silica films. The cracks appear on the silica film surface and further expand at larger γ-ray absorbed dose, while surface roughness slightly decreases. During γ-ray irradiation, the thermal effect and the increased rate of diffusion-controlled process lead to the condensation of Si-OH groups and the recombination of ODCs. However, the ionization of atoms leads to generation and accumulation of E′ centers and NBOHCs. γ-ray irradiation leads to the reductions of bond lengths and bond angles of Si-O-Si groups, thus causing the densification of films. The refractive index and mechanical property firstly enhance and then reduce with the increase of absorbed dose associated with the change of silica film density. After γ-ray irradiation, the decreased contact angle and increased surface free energy indicate the reduction of anti-pollution ability of silica films. The dose-dependent surface quality, defects and mechanical properties determine the variation in laser-induced damage threshold (LIDT) of silica film. The results provide a reference to control the structural damage and performance degradation of silica films, which is very important for the research of safe operation of high-power laser facilities for inertial confinement fusion (ICF).

A novel ultrafast laser ablation fracture polishing method to simultaneously smoothing and improving the surface quality of Al2O3 ceramics with high roughness

Al2O3 ceramics are widely used in industry due to their excellent mechanical and physical properties. However, microcracks, voids and high surface roughness (Sa) on the surface of Al2O3 ceramic parts produced in conventional industrial or additive manufacturing have been one of the technical bottlenecks limiting their high-performance applications. In this paper, a novel method of ultrafast laser ablation fracture polishing (ULAFP) of Al2O3 ceramic parts is proposed for improving the surface quality and enhancing the mechanical properties of the polished surfaces. The ULAFP method is developed with an ultrafast laser, which can be set up as a picosecond (PS) or a femtosecond (FS) laser. The PS laser is used to form a remelting layer on the surface to eliminate surface void defects. Combining laser ablation and laser thermal stress-induced crack extension effects, the FS laser is used to rapidly remove the remelted layer and obtain a surface free of crack defects and finally implement FS laser layer-wise ablation to achieve smoother surface finish. The FS laser energy density is controlled at a critical state close to the ablation threshold of the material to avoid surface defects. This ULAFP can reduce the surface roughness (Sa5.254 μm) polishing of Al2O3 ceramics to 0.80 μm, while controlling the total ablation depth of the polishing process to below 100 μm maintaining the dimensional accuracy of the part and dramatically improving the mechanical properties of the polished surface. Compared with the original surface, the hardness and elastic modulus of the polished surface improved by 104.6% and 63.9%, respectively.

Intelligent Additive Manufacturing Architecture for Enhancing Uniformity of Surface Roughness and Mechanical Properties of Laser Powder Bed Fusion Components

In the Laser Powder Bed Fusion (L-PBF) process, 3D components with complex geometries are fabricated in a layer-by-layer fashion by using a controlled laser beam to selectively melt particular regions of the metal powder bed. However, due to the stochastic nature of the L-PBF process, the top surface roughness of each solidified layer tends to be different even when the optimal processing conditions for the different positions on the build plate are employed. As a result, the mechanical properties of the built components frequently vary from one component to the next. Accordingly, this study proposes an Intelligent Additive Manufacturing Architecture (IAMA) for controlling the surface roughness of each build layer through an appropriate adjustment of the laser re-melting parameters. The IAMA architecture comprises five modules, namely In-Situ Metrology (ISM), Ex-Situ Metrology (ESM), Automatic Virtual Metrology (AVM), Additive Manufacturing Simulation (AMS) and Intelligent Compensator (IC). The feasibility of the proposed architecture is demonstrated by comparing the top surface roughness of cubic and mechanical strengths of tensile test samples built using the proposed method with those built using a traditional L-PBF approach without surface roughness control. It is found that the samples fabricated using the IAMA approach have an average top surface roughness of 1.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m and a standard deviation is 0.7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m. By contrast, the samples produced using the traditional L-PBF approach have an average surface roughness of 13.45 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m and a standard deviation of 2.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m. In addition, the specimens produced with the assistance of IAMA architecture have an average tensile strength of 1013 MPa with a standard deviation of 69.5 MPa, while those printed without surface roughness control have an average tensile strength of 903 MPa with a standard deviation of 101.4 MPa <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —As L-PBF produce part in a layer-by-layer manner, therefore, the roughness on the top surface of previous layer have a strong influence on the printing quality of current layer. The variations of surface roughness will lead to the fluctuation of mechanical properties of the fabricated components. Additionally, to the best of author’s knowledge, current commercial L-PBF machines can not actively control the surface roughness of samples during the process. The proposed IAMA in this work can predict and control the roughness on the top surface of each layer during L-PBF process. Therefore, the constructed architecture has strong potential for integrating into the commercial L-PBF machine for controlling the surface roughness on the top of the parts during the manufacturing process. As a result, the quality of the fabricated components is expected to be in consistent. Accordingly, L-PBF machine equipped with IAMA will have a strong potential in applying for mass production of the components in aerospace and automobile industries.

К вопросу о биосовместимости керамических имплантатов при оказании ортопедической помощи.

When organizing orthopedic care, specialists should be aware of scientific data regarding the ability of the zirconia implant system used to osseointegrate. The biocompatibility of implants depends on various parameters such as the nature of the material, chemical composition, surface topography, chemical composition and loading, surface treatment, physical and mechanical properties. Zirconium has a high biocompatibility with soft tissues, resistance to bacterial biofilms. Zirconia implants are a promising alternative to titanium, especially for titanium allergic patients.

Effect of laser surface remelting on Microstructure, mechanical properties and tribological properties of metals and alloys: A review

Surface defects like porosity, cracks, coarse grains, surface roughness, etc. have a huge impact on the strength and performance of materials. Due to this, surface treatments have become an important part in the field of materials to attain certain desirable mechanical properties and surface properties. Surface of parts treated with laser surface remelting exhibits excellent surface and mechanical properties. It is a computer-based technique which provides the advantage of treating selective surfaces. Laser surface remelting tends to enhance corrosion resistance, microhardness, wear resistance, fatigue strength, and tensile strength of the materials. To achieve certain mechanical properties with laser surface remelting, an optimized set of laser processing parameters is essential. Laser surface remelting has become a compulsory treatment for parts manufactured by Additive Manufacturing (AM) processes as these processes provide poor surface, porosity, and hot cracking defects which ultimately affect the performance of parts. This paper critically evaluates the advancements which have been made in the field of laser surface remelting to get better surface quality, improved mechanical and tribological properties.