Spark Plasma Sintering of Mg-based Alloys:Microstructure,Mechanical Properties,Corrosion Behavior,and Tribological Performance

Within the past ten years,spark plasma sintering(SPS)has become an increasingly popular process for Mg manufacturing.In the SPS process,interparticle diffusion of compressed particles is rapidly achieved due to the concept of Joule heating.Compared to traditional and additive manufacturing(AM)techniques,SPS gives unique control of the structural and microstructural features of Mg components.By doing so,their mechanical,tribological,and corrosion properties can be tailored.Although great advancements in this field have been made,these pieces of knowledge are scattered and have not been contextualized into a single work.The motivation of this work is to address this scientific gap and to provide a groundwork for understanding the basics of SPS manufacturing for Mg.To do so,the existing body of SPS Mg literature was first surveyed,with a focus on their structural formation and degradation mechanisms.It was found that successful Mg SPS fabrication highly depended on the processing temperature,particle size,and particle crystallinity.The addition of metal and ceramic composites also affected their microstructural features due to the Zener pinning effect.In degradative environments,their performance depends on their structural features and whether they have secondary phased composites.In industrial applications,SPS'd Mg was found to have great potential in biomedical,hydrogen storage,battery,automotive,and recycling sectors.The prospects to advance the field include using Mg as a doping agent for crystallite size refinement and using bulk metallic Mg-based glass powders for amorphous SPS components.Despite these findings,the interactions of multi-composites on the processing-structure-property relationships of SPS Mg is not well understood.In total,this work will provide a useful direction in the SPS field and serve as a milestone for future Mg-based SPS manufacturing.

A comprehensive review on the processing-property relationships of laser strengthened magnesium

Among the existing series of softer metals,magnesium(Mg)has attracted much attention due to its impressive strength-to-weight ratio.However,due to its ease of deformability,Mg tends to suffer from rapid degradation in a wide variety of abrasive and electrochemical environments.One method of improving its surface properties is through surface modification techniques.Among the existing techniques,laser shock peening(LSP)has been one of the most widely utilized processes due to its surface-hardening-like effects.Despite this understanding,a comprehensive review has yet to exist that encapsulates the strengthening mechanism of LSP for Mg and its influence in degradation environments.This review aims to encapsulate the existing research around the LSP field for Mg.Specifically,an understanding of the surface-strengthening effects in relation to its mechanical,tribological,corrosion,and tribo-corrosion characteristics is elucidated.Additionally,the feasibility of LSP for Mg materials in critical industries is also discussed.Through this work,a novel understanding of LSP for Mg can be understood,which can provide a future direction for research in this field.

Surface modification of magnesium alloys using thermal and solid-state cold spray processes:Challenges and latest progresses

Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.

Direct ink writing to fabricate porous acetabular cups from titanium alloy

Acetabular cups,which are among themost important implants in total hip arthroplasty,are usually made from titanium alloys with high porosity and adequate mechanical properties.The current three-dimensional(3D)printing approaches to fabricate customized acetabular cups have some inherent disadvantages such as high cost and energy consumption,residual thermal stress,and relatively low efficiency.Thus,in this work,a direct ink writing method was developed to print a cup structure at room temperature,followed by multi-step heat treatment to form microscale porous structure within the acetabular cup.Our method is facilitated by the development of a self-supporting titanium-6 aluminum-4 vanadium(Ti64)ink that is composed of Ti64 particles,bentonite yield-stress additive,ultraviolet curable polymer,and photo-initiator.The effects of Ti64 and bentonite concentrations on the rheological properties and printability of inks were systematically investigated.Moreover,the printing conditions,geometrical limitations,and maximum curing depth were explored.Finally,some complex 3D structures,including lattices with different gap distances,honeycomb with a well-defined shape,and an acetabular cup with uniformly distributed micropores,were successfully printed/fabricated to validate the effectiveness of the proposed method.

Tribological interactions of 3D printed polyurethane and polyamide with water-responsive skin model

3D printing in the textile and fashion industry is a new emerging technology.Applications of 3D printing for designing clothes and other wearable accessories require tribological and biological understanding of 3D printing plastics against the complex human skin to mitigate skin-friction related ailments such as calluses and blisters.This study provides tribological insight in search of an optimal 3D printable material that has minimal friction against the skin.Two low friction 3D printable materials,thermoplastic polyurethane(TPU)and polyamide(TPA)were chosen and tribological testing was carried out against a water responsive skin model.The skin model was synthesized using a gelatine based model made with cotton and crosslinked with glutaraldehyde.Tribological testing of TPU/TPA against the skin model in dry and wet conditions were made.The higher coefficient of friction(COF)was observed in the wet condition compared to the dry condition.To overcome the higher friction,TPA/TPU-sodium polyacrylate composites were prepared by heat pressing that significantly reduced COF of TPU and TPA by~40%and 75%,respectively,in wet conditions.