Cold sprayed polymer substrates offer a promising platform for bridging electroless deposition methods and applications. This study’s contribution to the field is the combination of cold sprayed polymer substrate and the electroless-plating process. In simulation, finite element analysis of the as-sprayed polymer substrate using a viscoelastic model that considers large strain time-dependent behavior were conducted. A three-network constitutive model was applied to capture the non-linear and time-dependent response of large strain polymer deformation. In experiment, the process-structure-property relationship was examined from the as-sprayed specimen to the final coated electroless-plated samples. A controlled coating process of Cu powders was first cold sprayed on polyamide 6. The as-sprayed specimen was then electroless deposited. Mechanical testing was performed on as-sprayed specimens and adhesion testing was performed on electroless deposited specimens. Scanning electron microscopy (SEM) was employed to observe the surface and the cross-section of the as-sprayed and electroless deposited specimens. Lastly, the behavior of Cu coated specimens immersed in KOH solution was examined by cyclic voltammetry.

The biocompatibility, mechanical properties and biodegradable nature of Mg alloys have made them attractive for biomedical applications, especially as bone implants. However, one of the main problems that limit the use of Mg alloy for several biomedical applications is their fast corrosion rates inside the body. Coating Mg-based implants is one of the most extensively studied approaches to address the fast corrosion rates of Mg alloys in the physiological environment. Micro arc oxidation (MAO) coating process has shown very promising results towards reducing the corrosion rates of Mg alloys due to the formation of a protective dense, well-adhered and wear-resistant oxide layer on the surface of the Mg alloy. In this study, the feasibility of coating an Mg-Zn-Ca-based alloy with a composite coating made using a micro-arc oxidation coating process and an immersion (dipping process) was investigated. The corrosion properties and surface characteristics of the coated alloy samples are assessed. The created protective composite coating is used to slow the corrosion rates of an Mg-Zn-Ca-based alloy. The developed composite coating resulted in a significant reduction in the corrosion rates. The results of this study show that it is possible to achieve more controlled corrosion rates of Mg-based implants towards patient-specific bone implant applications.

Laser Beam Machining (LBM) is one of the versatile non-traditional manufacturing processes. Material removal in LBM is based on high heat flux generated by laser beam which melts and vaporizes the workpiece material in the focused point. Laser Beam Machining process can shape almost all range of engineering materials from metallic alloys to non-metallic alloys as well as composite materials. But one of the main limitations of laser beam machining is the machining of reflective materials. When laser beam is focused on the reflective surface, part of the energy is reflected by the surface and the remaining is absorbed. In this study, an attempt has been made to increase the absorptivity of the reflective material by coating anti-reflective coating on the surface of the material. Glass has been used as reflective material in this study because of its extensive applications in the micro-opto-electro-mechanical systems. The optimal machining depends on both laser parameters and properties of the workpiece material. There are number of laser parameters that can be varied in the laser machining process. It is difficult to find optimal laser parameters due to mutual interaction of laser parameters. A statistical study based on design of experiment (DoE) has been made to study the effect of anti-reflective coating and parameters like laser power, laser scanning speed, angle of inclination of the workpiece on depth of the slot, width of the slot, aspect ratio and material removal rate (MRR) in the laser machining process using 2 k factorial design and ANOVA. On an average 4 times increase in depth of the slot, 2 times increase in width of the slot and 7 times increase in the MRR was observed in the glass work samples with anti-reflective coating when compared to glass work samples without anti-reflective coating.

The friction surfacing technique is a new variation of friction stir welding process for modification of the surface properties of the substrate. There is a growing body of literature dealing with friction surfacing by consumable tool. This is a metallic deposition technique in which a rotating consumable tool deposits material onto a solid substrate. Friction surfacing has many applications in welding, coating, repair of defective components, hard surfacing and corrosion protection. This process does not generate high temperatures; therefore this technique is a suitable coating method capable of joining low melting point alloys. This review paper studies the basic principles and the use of friction surfacing as well as a survey of the latest researches and applications with emphasis on superficial and microstructural characterization, tensile, bending, effects of the different process factors such as axial force, rotation and travel speed, material deposition rate, energy consumption and different tool types. This review shows there are a few investigations dealing with novel tool/workpiece configurations for adding material for purposes other than coating, such as keyhole filling or dissimilar material joining. Also, the possible future directions for development and application of this technique are presented.

This paper aims to investigate the effectiveness of several superhard ceramic coatings on carbide drills when drilling carbon fiber reinforced plastics (CFRP) composite/Ti-6Al-4V alloy (titanium or Ti) stacks. The drilling experiments of CFRP/Ti stack are conducted with diamond-like coating (DLC) coated, alternating layers of the nanocomposite of AlCrN & Si3N4 and TiN or (AlCrSi/Ti)N coated, and uncoated tungsten carbide drills. Tool wear evolution of each drill is measured qualitatively as well as quantitatively using the scanning electron and confocal laser scanning microscopes (CLSM) by interrupting after making certain numbers of hole. Based on our drilling experiments, the performance of each coating when drilling CFRP/Ti stack are discussed. Among these coated and uncoated drills, uncoated and DLC coated drills failed before making 5 holes while (AlCrSi/Ti)N coated drills performed the best making more than 80 holes. The DLC coating, despite of high hardness of DLC coating, does not provide any significant protection especially when drilling Ti layer.

High-resolution 3D measurement is crucial for a wide range of applications in manufacturing. With the recent development of optical technologies, the performance of many 3D scanning systems has entered the practical range for object digitizing, reverse engineering, quality control, and many other manufacturing applications. In order to extend the measurement capability to reflective or transparent surfaces, a common practice for reducing the unwanted reflection and refraction is to coat the surfaces with micro-particle spray. There is, however, limited discussion about the influence of coating spray on the resulted measurement precision of 3D optical scanning systems, and due to lack of standardized procedure for spray coating, the variability caused by different operators in surface measurement remains to be examined. This paper investigates the 3D data acquisition of spray-coated surfaces with a structured-light scanning system through experiments and statistical analysis. Both surface roughness and spatial statistics are used to quantitatively evaluate the characteristics of the 3D measurement system. Gauge R&R study is conducted to determine measurement repeatability and reproducibility. The results demonstrate that both the number of spray pass and the skill of the individual operator can significantly affect the performance of the structured-light scanning system. Other pertinent suggestions for the operation of 3D optical scanning systems with spray coating are also provided.

Rotational atherectomy (RA) utilizes a high-speed diamond grinding wheel to remove the calcified atherosclerotic plaque off the vessel wall via a catheter inside an artery for blood flow restoration and treatment of cardiovascular diseases. RA in angulated lesions is challenging due to the geometric constrains on the wheel motion, potentially leading to vessel dissection and perforation. To understand the grinding wheel motion and force during RA in curved arteries, experiments were conducted based on 3D printed anatomically accurate coronary artery phantoms with plaster coating as the plaque surrogate, a high-speed camera, and a multi-axis force transducer. Results showed that the grinding wheel did not orbit inside right coronary artery phantom which led to a highly biased ground region aligned with several contact points between the guidewire and the arterial wall. The grinding wheel orbital motion facilitated an even treatment of several segments in left anterior descending coronary artery phantom. The grinding force, ranging from 0.05 to 0.20 N, increased with the wheel rotational speed when the wheel orbited and was insensitive to the wheel speed without wheel orbital motion. This study explained the clinically observed guidewire bias from the engineering perspective and further revealed the RA mechanism of action in angulated artery, which may assist to improve the device design and the operating technique.

The effect of graphene nanoplatelets (GNPs) on enhancing the interlaminar fracture toughness of glass fiber/epoxy composites was investigated. The GnPs were physically deposited on the fiber surface by the dip coating technique. The composites were fabricated by hand layup technique followed by the compression molding process. Mode-I fracture test was conducted on the composite specimens. Crack propagation was studied by the digital image correlation (DIC) technique. Mode-I fracture toughness for composites loaded with 0.5 wt.% GnPs showed improvement by an average of 60% when compared to the pristine composites. It is concluded that the addition of GnPs produces a strong fiber/matrix interface bonding which effectively limits the crack propagation.

Low frequency vibration assisted drilling (LFVAD) is regarded as one of the most promising process in CFRP/Ti stacks drilling. This work carries the investigation of the difference between conventional drilling and LFVAD based on kinematic model. The experiments are conducted under varied vibration amplitude to a specific feed rate, also under varying spindle speeds, feed rates when the ratio of amplitude to feed rate is fixed. Then the hole quality of CFRP is evaluated based on the analysis of drilling force, chip morphology, chip extraction. The results show that there is rarely no difference between conventional drilling and LFVAD in drilling mechanism when the drilling diameter is over 1 mm. Because the impact effect caused by drill vibration is already weak. It is found that the severe mechanical damage of the CFRP holes surface could be significantly reduced due to the fragmented chips obtained in vibration drilling. The maximum instantaneous feed rate combined with feed rate and amplitude plays a significant role in CFRP hole quality. Lower maximum instantaneous feed rate results in better hole wall quality and less entry delamination. Spindle speed has no visible influence on entry delamination, while higher spindle speed improves the hole surface quality due to the resin coating phenomenon.

Fused-coating based metal additive manufacturing (FCAM) is a newly established direct metal forming process. This method is characterized by deposition metal materials in a crucible and under the driving pressure the molten metal is extruded out from a special designed nozzle. Hence, dense metal parts with different kind of materials can be built on the moving substrate layer by layer. It provides a method to fabricate metal components with lower costs, clean and cheap materials compared with other AM processes. To study the feasibility of this new AM methodology, an experimental system with a molten metal stream generator, a fused-coating nozzle, a process monitor unit, an inert atmosphere protection unit and a temperature measurement unit has been established. In order to determine the proper parameters in the building process, a metal fused-coating heat transfer model analysis and experimental study is performed by using Sn63-37Pb alloy in building three-dimensional components. The process parameters that may affect fabrication are molten and substrate temperature, layer thickness, the substrate-speed, the temperature of substrate, the distance between the nozzle and substrate and the pressure. Microscopy images were used to investigate the metallurgical bonding between layers. The influence of different parameters on the layer thickness and width was studied quantitatively. At last, the optimal parameter was used to fabricate complex metal parts to demonstrate the feasibility of this new technology compared with other AM methods.

The current study focuses on the process monitoring of thermal history and its significance in laser cladding technology. Thermal history of the molten pool during laser cladding was monitored using an IR-pyrometer and the molten pool life time, solidification shelf duration and cooling rates were calculated. Effect of these on three different cases was studied in brief: (a) Elemental segregation in nickel based super alloy, (b) Wettability between metal matrix and WC particles and (c) Decomposition of TiC particles in metal matrix. It was found that with slow cooling rate, formation of Laves phases in Inconel 718 became dominant which is detrimental to the mechanical properties. Also, slow cooling resulted in the decomposition of TiC particles resulting in poor wear properties of the coating. In contrast to the above two cases where slow cooling was found to be detrimental for mechanical properties of the coating, it increased wettability as well as bonding through diffusion between the WC particles and the metal matrix. Also the effect of presence of TiC and WC in metal matrix on molten pool thermal history was studied. The microstructures, elemental segregations and fractured surfaces were characterized using SEM and EDS analyses.

The fast corrosion rate of magnesium (Mg) alloys is the main problem associated with the use of such biocompatible alloys for bone fixation applications. The corrosion resistance of Mg alloys can be improved by different post-fabrication processes such as heat treatment and coating. We have heat-treated a biocompatible Mg-1.2Zn-0.5Ca (wt.%) alloy at optimized heat treatment parameters to achieve the highest mechanical strength and corrosion resistance. Afterwards, the heat-treated alloy was coated with a ceramic layer using micro arc oxidation (MAO) process to further enhance the corrosion resistance. The microstructure of the prepared samples was investigated using optical microscopy and scanning electron microscopy (SEM). The corrosion characteristics were determined by conducting in vitro electrochemical and immersion corrosion tests. The results showed that the heat treatment process successfully improved the mechanical and corrosion properties of the Mg-1.2Zn-0.5Mn (wt.%) alloy. Both the in vitro electrochemical and immersion corrosion tests showed that the MAO-coated samples have a significantly higher corrosion resistance which results in a significantly lower corrosion rate. This study indicated that the biocompatible coating produced by MAO process may be suitable for providing heat-treated Mg-Zn-Ca-based alloys with protection from corrosion towards synthesizing bone fixation materials in clinical application.

Alumina powder was sprayed on low carbon steel substrate using atmospheric plasma spray process. Two different powders namely crushed and agglomerated powders were used and current was varied to study their effect on fracture toughness. Theoretically, with increase in arc current, melting of ceramic oxide shall increases and in turn dense coating should form. However, it was observed that if the arc power is too high and particle size of the powder being small (∼ 30 μm), the particles tend to fly away from the plasma core. Similarly, particle size distribution and powder morphology also affects the coating properties. Smaller particle should allow more melting resulting in dense coating and agglomerated powder allows flowability as well as better coating efficiency. Conversely, smaller particles tend to fly away from the plasma making the process difficult while the agglomerated particles showed a bimodal structure marked by presence of unmelted region in the splat core. All these factors lead to substantial variation in the fracture toughness of the coating. The present paper attempts to correlate plasma spraying parameters and microstructure of the coating with fracture toughness of the same.

Commercially pure titanium (CP-Ti) attracts a large number of attentions in biomedical, astronautical, and auto industrial areas due to its superior properties of good biocompatibility, excellent corrosion resistance, and high strength-to-weight ratio. Comparing with the conventional manufacturing processes (such as casting along with machining), laser additive manufacturing (LAM), mainly including selective laser sintering/melting (SLS/M) and laser engineered net shaping (LENS), has many advantages, such as complex shaped parts producing, more capability of shorter design-to-market time, energy consumption reducing, etc. It was reported that SLS/M has been successfully used in fabricating of CP-Ti components. Comparing with SLS/M processes, LENS has many advantages, including lower labor intensity, higher fabrication efficiency, and more capabilities for parts repairing and rebuilding. It is reported that LENS process was only used in CP-Ti coating and porous parts fabrication, there are no reported investigations on CP-Ti three-dimensional (3D) solid parts using LENS process. The investigations in this paper are going to conduct preliminary studies on effect of fabricating variables. In order to evaluate powder efficiency and parts’ quality, heights of fabricated parts and hardness on the top surface of the parts will be tested.

To improve the copper absorption coefficient to lasers, and to realize a high welding quality with a low power laser machine, a black-treating method was proposed in this study. With this method, the reflection coefficient of the copper to lasers with 1064nm wavelength could be reduced from 95% to 15.5%. The experimental study of copper welding with a 500 W fiber laser machine was carried out. The shape, the strength and the micro-hardness of the welding seam with different welding velocity and defocus amount were compared. And, the best welding parameter was obtained. Moreover, the laser welding quality of copper with black-treating and that with graphite coating was compared, and the result showed that the micro-hardness and the strength of the welding seam of copper with black-treating was better than that with graphite coating.

Alumina ceramic is a high performance engineering material with excellent properties, including high melting point, high hardness and brittle nature make the alumina ceramic difficult to machine and needing high cost by using conventional manufacturing methods. Coating is an important method for alumina fabrication. The excellent properties of coatings can be used for special surface protection and ceramic parts repairing. Comparing with other coating methods, laser cladding method has many good properties to overcome the drawbacks. The reported investigations on laser cladding provide little information about alumina materials for ceramic coating. In this paper, effects of different input variables of laser cladding of alumina materials for ceramic coating were studied. And this paper for the first time reported the relationship between the properties (including surface roughness, flatness and powder efficiency) and input variables such as laser power, powder feeding rate and laser head moving rate. The obtained results will be helpful to establish efficient and effective processes for ceramics coating.

This paper presents the development process of a new coating method for Micro pencil grinding tools (MPGT). MPGTs, applied for micro grinding, consist of a base body, abrasives and a metallic bond. The manufacturing process of these micro tools presents two challenges. The first being in finding a method to embed the abrasives with a uniform grit distribution and the second finding the correct parameters, required for a bond with adequate grit retention forces. In this research an electroless plating process is presented. Both the abrasive grit distribution method and the plating parameters will be presented in this paper.

Functionally graded bioactive glass coatings on bioinert metallic substrates were produced by using continuous-wave (CW) laser irradiation. The aim is to achieve strong adhesion on the substrates and high bioactivity on the top surface of a coating material for load-bearing implants in biomedical applications. The morphology and microstructure of the bioactive glass from the laser coating process were investigated as functions of processing parameters. Laser sintering mechanisms were discussed with respect to the resulting morphology and microstructure. It has been shown that double layer laser coating results in a dense bond coat layer and a porous top coat layer with lower degree of crystallinity than an enameling coating sample. The dense bond coat strongly attached to the titanium substrate with a ten microns wide mixed interfacial layer. A highly bioactive porous structure of the top coat layer is beneficial for early formation of a bone-bonding HCA layer. The numerical model developed in this work also allows for prediction of porosity and crystallinity in top coat layers of bioactive glass developed through laser induced sintering and crystallization.

Improving the machinability of titanium (Ti) alloys remains unresolved for manufacturing industries because excessive tool wear and catastrophic tool failures lead to shortened tool life and low productivity with any available cutting tool system. Besides optimizing the substrate and/or coating materials for cutting tools, improving the cooling and lubricating conditions is one of the ways to improve the machinability of Ti alloys. In this paper, we explore the possibility of using a nano-platelet, lamellar-type solid lubricant of graphite Exfoliated graphite nano-platelets (xGnP ® ) grade C750 (or xGnP750) in Minimum Quantity Lubrication (MQL) machining of Ti-6Al-4V (Ti64). Due to the lamellar or layered crystal structure, each layer easily slides against adjacent layers to provide the lubricity when introduced at the tool/work material interface. Although the nano-platelets have a nano-thickness, they have a micro-sized diameter, which prevents the nano-platelets from penetrating through human skin and breathing through nose. This makes the great advantage in this approach compared to other nano-enhanced MQL processes. The milling experiment shows that the nano-platelets present in the MQL oil decreased flank wear and improved the tool life compared to traditional MQL with pure oil as well as dry machining. The presence of nano-platelets reduces the micro chipping and tool fracture caused by the effect of impact in interrupted machining.

Product manufacturing systems are one of the largest energy consumers. Focusing on the production of the automobile body coating in particular, the authors investigate the drying system of coating line to improve the energy efficiency during the drying process of the parts. First, The flow field of a drying room is simulated with FEM. Then, an applicable regulation system for controlling the energy loss is built. The proposed method effectively improves the energy utilization of the drying system; thus, decreasing energy loss.