bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low Pressure Cold Gas Dynamic Spray and Post-Spray Heat Treatment of Composite Coatings
Authors: Maev R. , Beneteau M. , Birtch W. , Villafuerte J. , Sastry K.Y. , Leshchynsky V. 
Published: September 2022

Abstract
This paper describes the influence of post-spray heat treatment parameters on mechanical properties of Ni-TiC composite coatings. Thin Ni-TiC composite coatings were produced by low pressure cold gas dynamic process (also referred as cold spray or kinetic spray process) on an Inconel alloy substrate. In the coating process, mechanically mixed micron-sized Ni-TiC powders (~50 µm) were injected into a de-Laval nozzle propelled by a supersonic gas stream to high velocity (&gt;300 m/s) to impinge upon a substrate. The coatings are formed subsequently as the metallic particles are severely deformed plastically and bonded to both the substrate and to one another. However the tensile adhesion strength levels were determined to be in the range of 10-14 MPa. A subsequent post-spray heat treatment in vacuum was found to enhance the bond strength of the coated particles with the substrate due to good metallurgical bonding caused by diffusion mechanism.
Microstructure and Mechanical Properties of Low-Pressure Cold Sprayed (LPCS) Coatings
Authors: Koivuluoto H. , Lagerbom J. , Kylmälahti M. , Vuoristo P. 
Published: September 2022

Abstract
In low-pressure cold spray (LPCS) process, compressed air is used as a process gas. The most important process parameters are the gas (air) preheating temperature and the gas pressure. Maximum preheating temperature of air is 650ºC and pressure is 9 bar in the LPCS system used in the present study. Powders used in LPCS process contain hard particles (Al2O3) with metallic powders. LPCS is the method to spray soft metallic coatings with ceramic hard phase for different application areas. For example LPCS opens a way to produce thick coatings for electrical and thermal conductive applications and for corrosion protection. Aim of this study was to investigate microstructural properties such as microstructure and denseness of LPCS coatings. Also mechanical properties (hardness and bond strength) were studied. One interest of this study was to clarify the effect of hard phase on different coating properties. Coating materials were Cu, Ni, and Zn. Substrate material were carbon steel and copper. LPCS coatings seemed to be dense according to SEM studies but corrosion tests were needed to identify existence of porosity. Through-porosity was observed in the structures of the LPCS coatings during the corrosion tests. Bond strengths of LPCS Cu and Zn coatings were found to be reasonable and furthermore, hardnesses were quite high indicating reinforcement effect of hard phase and work hardening.
Influence of Laser Irradiation on Formation of Low-Pressure Cold Sprayed Coatings
Authors: Kulmala M. , Koivuluoto H. , Vuoristo P. 
Published: September 2022

Abstract
In cold sprayed coatings, the technical properties are besides the coating material itself also highly determined by the integrity of interparticle boundaries and coating to substrate interface. One possibility to affect these boundaries is a simultaneous laser irradiation during the cold spray process. It is expected that laser-assisted low-pressure cold spraying could be an effective method to improve the low-pressure cold sprayed coating denseness and adhesion. The purpose of the additional energy from the laser beam is to create denser and more adherent coatings, enhance deposition efficiency and increase the variety of coating materials. In this study copper and nickel powders with additions of alumina powder were laser-assisted low-pressure cold sprayed (LALPCS) on carbon steel. Coatings were sprayed using nitrogen or air as process gas. A 6 kW diode laser or 4 kW Nd:YAG laser and low-pressure cold spraying unit were used in the experiments. The influence of laser energy on coating microstructure, denseness and deposition efficiency was studied. The coating microstructure was characterized by a scanning electron microscope (SEM). The coating denseness was tested with open cell potential measurements and salt spray tests. Results showed that laser assistance made coatings denser and also enhanced deposition efficiency.
Axial Injection Plasma Spraying using Micro and Nanopowder Slurries to Produce Dense Ceramic Coatings
Authors: Tang Z. , Yaroslavski I. , Hartell P. , Bogdanovic N. , Burgess A. 
Published: September 2022

Abstract
Plasma spraying was successfully applied for Thermal Barrier Coatings (TBCs), which typically possess a lamellar structure with a porosity of 5-20%. Control of the plasma process presents a big challenge when the goal is to achieve fully dense coatings, as required for some emerging applications such as solid oxide fuel cells (SOFCs) and dense TBCs. Fine powders produce finer lamellae, and result in denser coatings. However, powders finer than 10 microns are very difficult to feed consistently into a plasma torch. Liquid slurries offer a means to deliver fine particles to thermal spray torches. In this paper, an automatic slurry feed system was developed to consistently deliver micro and nano powder slurries. The slurries were injected axially into a high energy/high velocity plasma torch to generate dense coatings. The effects of plasma parameters and different feedstocks on coating microstructures are investigated; dense coatings for various applications are demonstrated.
Plasma Spray Processing of Nanostructured Partially Stabilized Zirconia for a Strain Accommodating Inter-Layer – Splat Characteristics
Authors: Guru D. , Heberlein J. 
Published: September 2022

Abstract
Build up of strain within thermal barrier coatings has been identified as one of the main reasons for coating failure. The large volume fraction of grain boundaries in nanostructured materials has been predicted to partially relieve the strain in a coating structure. In this study, the difference in morphological characteristics of regular PSZ (r-PSZ) particles and nano-agglomerate PSZ (n-PSZ) particles have been investigated to improve our understanding of the stresses and strains within a coating. The Triple Torch Plasma Reactor, a reduced pressure plasma spray system along with a pair of tungsten and molybdenum apertures was used to isolate spray particles from the plume to deposit splat sample. Cross sections of the splat samples were prepared. Image analysis techniques were used on scanning electron microscopy (SEM) images to characterize both the surface and the cross sectional features of the splat samples. Semi-molten structures were found to be the defining characteristic of the n-PSZ samples. Peak height distribution (PHD) was defined to quantify the distribution of the height of semi-molten structures. PHD was estimated for different samples and was found to track the changes in the morphological characteristics as a function of the deposition conditions.
Research of Properties of Nanostructured Cr2O35SiO23TiO2 coatings by plasma sprayed
Authors: Li Z. , Yu Y. , Zeng K. , Song X. , Zhou H. , Wu C. 
Published: September 2022

Abstract
Plasma sprayed chromium oxides coatings have been widely applied in anilox rolls and pump seal for many years. This paper is researching the effect of nanostructured Cr2O35SiO23TiO2 composite powder preparation when adding nano-size SiO2 and TiO2 powder in Cr2O3 powder, to prepare for through spray drying, high temperature sintering and flame density. The microstructure of powder and plasma sprayed coating are analyzed by SEM and XRD, compared with pure Cr2O3 powder and METCO 136F powder. The Microhardness of the coatings are measured by 402MVATM Vickers hardness tester. Fracture test is used to analysis the ductility of coatings, and the fracture appearance is analyzed by SEM. The result indicates that the mechanical behaviors of nanostructured Cr2O35SiO23TiO2 coating has better performance in the nature of hardness and ductility.
The Effect of Surface Chemistry and Morphology on the Properties of HVAF PEEK Single Splats
Authors: Withy B.P. , Hyland M.M. , James B.J. 
Published: September 2022

Abstract
Thermal spray of polymers has had limited investigation due to the narrow processing windows that are inherent to polymer powders, especially their low temperatures of thermal degradation. The polymer poly aryl ether ether ketone (PEEK) has a high thermal degradation temperature and high resistance to alkaline and acidic attack. These properties led to PEEK being selected for investigation. To minimise thermal degradation of the particles, the high velocity air fuel (HVAF) technique was used. To investigate the effect of substrate pre-treatment on single splat properties, single splats were collected on aluminium 5052 substrates with six different pretreatments. The single splats collected were imaged by scanning electron microscopy (SEM) and image analysis was performed with ImageJ, an open source scientific graphics package. On substrates held at 323°C it was found that substrate pretreatment had a significant effect on the circularity and area of single splats, and also on the number of splats deposited on the substrates. Increases in splat circularity, area, and the number of splats deposited on the surface were linked to the decrease in chemisorbed water on the substrate surface and the decrease of surface roughness. This proved that surface chemistry and roughness are crucial to forming single splats with good properties, which will lead to coatings of good properties.
Ceramics as Wear and Corrosion Protection on Hydraulic Piston Rods
Authors: Kraak T. , Coolegem G. , Herlaar W. 
Published: September 2022

Abstract
The application of thermal sprayed coatings has a broad industrial scope, not only applied where it concerns repairing but also as a preventive means. This article focuses on the applications of ceramics as wear and corrosion protection on hydraulic piston rods. It begins with a concise description of the different forms of wear and their mechanisms with some typical examples of worn surfaces. This is followed by an overview of the available coating techniques for enhancing metal surfaces. Next, the article discusses the principle and applications of thermal sprayed coatings. Then, it presents the scope and protection measures of thermal sprayed coatings to failure mechanism. Further, the article discusses the properties, quality control, and testing criteria of the coatings. It describes the chemical composition and chemical analysis of quality control spray powder. Finally, the article ends with a discussion on the examples of thermal sprayed coatings in OEM applications.
New Structure of APS Sprayed AI2O3 Coatings Investigated by Cu-Electroplating
Authors: Adachi M. , Takabatake T. , Ohmori A. , Kremer M. 
Published: September 2022

Abstract
A copper electroplating method revealed that recently developed commercial Al2O3 thermal spray coatings did not have the well-known lamellar structure but instead had a structure that was made up of tightly bonded particles, with many vertical microcracks in the coating. The coating in the study was prepared by the atmospheric plasma spray system. The copper electroplating method was applied to observation of the Al2O3 thermal spray coating structure. Spray coating specimens were electroplated in an aqueous solution containing CuSO4, H2SO4, CuCl2, and additives so that copper was deposited in small pores and narrow cracks in the coatings. Copper in the Al2O3 coatings was observed clearly by scanning electron microscopy, which also revealed the coating’s structure (boundaries of flattened particles and vertical cracks). The coating did not have a lamellar structure (horizontal apertures between flattened particles) and it was dense in spite of the many microcracks.
Thermal Failure of Nanostructured Thermal Barrier Coatings with Cold Sprayed Nanostructured NiCrAlY Bond Coat
Authors: Zhang Q. , Li Y. , Zhang S.-L. , Wang X.-R. , Yang G.-J. , Li C.-X. , Li C.-J. 
Published: September 2022

Abstract
Nanostructured YSZ is expected to exhibit a high strain tolerability due to its low Young’s modulus and consequently high durability. In this study, a porous YSZ as the thermal barrier coating was deposited by plasma spraying using an agglomerated nanostructured YSZ powder on a Ni-based superalloy Inconel 738 substrate with a cold-sprayed nanostructured NiCrAlY as the bond coat. The heat treatment in Ar atmosphere was applied to the cold-sprayed bond coat before deposition of YSZ. The isothermal oxidation and thermal cycling tests were applied to examine failure modes of plasma-sprayed nanostructured YSZ. The results showed that YSZ coating was deposited by partially melted YSZ particles. The nonmelted fraction of spray particles retains the porous nanostructure of the starting powder into the deposit. YSZ coating exhibits a bimodal microstructure consisting of nanosized particles retained from the powder and micro-columnar grains formed through the solidification of the melted fraction in spray particles. The oxidation of the bond coat occurs during the heat treatment in Ar atmosphere. The uniform oxide at the interface between the bond coat and YSZ can be formed during isothermal test. The cracks were observed at the interface between TGO/BC or TGO/YSZ after thermal cyclic test. However, the failure of TBCs mainly occurred through spalling of YSZ within YSZ coating. The failure characteristics of plasma-sprayed nanostructured YSZ are discussed based on the coating microstructure and formation of TGO on the bond coat surface.
Single Impact Erosion Studies of Cr3C2-NiCr Coating: The Role of Microstructure Variation
Authors: Matthews S. , Hyland M. , James B. 
Published: September 2022

Abstract
Cr3C2-NiCr thermal spray coatings have been extensively applied to mitigate erosion in high temperature applications such as aircraft and power generation turbines. Much laboratory based erosion research has been conducted under ambient temperature and mild erosion conditions. However, little has been presented about the coating response under the high temperature, high velocity erosion conditions typically experienced in industrial applications. This work presents the mechanisms of high velocity erosion based on experiments conducted under realistic service conditions. Single impact studies were carried out on a range of Cr3C2-NiCr coatings to assess the variation in erosion mechanism with phase degradation and starting powder morphology. Comparisons were made between the coating response in the as-sprayed state and after long-term heat treatment to determine how the erosion response changes as a function of exposure time in-service. Erosion of the as-sprayed coatings was heavily influenced by splat boundary related mass loss mechanisms. This was accentuated by in-flight carbide dissolution in the coatings based on agglomerated/sintered powders. Heat treatment led to splat sintering and a transition in the erosion response towards more microstructural based erosion mechanisms. The variation in erosion response as a function of microstructural development with heat treatment and starting powder type is presented.
Evaluation of Intermetallic Coatings Processed by PTA
Authors: d'Oliveira A. , de Christo A. , Vaz D.S. 
Published: September 2022

Abstract
Plasma Transferred Arc hardfacing (PTA) is an excellent tool for surface tailoring as it allows for the manipulation of coatings chemical composition. In particular in-situ alloy development can be achieved during the deposition of different powder mixtures. In this work powder mixtures of Ni-Al, Nb-Al and Fe-Al were deposited by PTA. Coatings were characterized for their mechanical features at room temperature evaluated by Vickers microhardness under 300gf load, nano- (0.04gf) and macro- (10kgf) scratch tests and pin-on-abrasive disc tests under 1kgf. Results showed very high dilution for the processed coatings with Vickers microhardness varing with the chemical composition of the deposited powder, mixtures, with the Fe based deposits exhibiting the lower hardness (below 400Hv) and the Nb-based deposits reaching 900HV. Scratch hardness followed Vickers micro hardness only for the Nb based coatings. Abrasion mechanism also varied for each alloy system and within each alloy system, the harder the coating the better the abrasive wear resistance. However when comparing the full set of coatings the Nb based coatings exhibited a superior performance and the Ni based deposits the poorer wear resistance.
Thermally Sprayed TiO2-Cr2O3 Coatings with Multifunctional Properties
Authors: Stahr C.C. , Berger L.-M. , Thiele S. , Saaro S. 
Published: September 2022

Abstract
Thermally sprayed titanium suboxide (TiOx) coatings are widely used in industrial applications due to their good tribological properties and their electrical conductivity. These properties are mainly dependent on the amount of oxygen in the crystal lattice. Oxygen defects lead to the formation of so-called Magnéli phases. The range of applications is limited by the fact that TiOx tends to reoxidize in many service conditions, especially at elevated temperatures. Also, the extreme conditions in the flame or torch used in the thermal spray process lead to undefined phase changes and defects. In the TiO2-Cr2O3 system, Magnéli phases are also formed, but it is assumed that the properties do not change due to oxidation during spraying and subsequent use. This work shows the possibilities of the new coating materials. Powders with different TiO2 and Cr2O3 contents and prepared by different technologies were used for the investigation of coating properties. Experimental powders with defined phase compositions were prepared. The powders were thermally sprayed and the coatings investigated in terms of phase composition, microstructure, hardness, and abrasion wear resistance.
Mechanically Activated Synthesis of Composite Powders for Thermal Spraying
Authors: Ilyuschenko A.F. , Belyayev A. , Talako A. , Letsko A. , Borovick D. 
Published: September 2022

Abstract
Known methods of production of composite powders have a series of deficiencies. The method of self-propagating high-temperature synthesis which has appeared recently has conclusive advantages. The method allows forming in a single work cycle micro and a macrostructure of a composite particle. The present work is devoted to viewing of questions targeted mechanical activated synthesis of composite powders for thermal spraying of function coating of various applications. Results of synthesis of powders Ti and Cr carbides in oxygen atmosphere are given.
Structure and Properties of Powders of Quasicrystalline Alloy AlCuFe Alloyed by Cr and Sc
Authors: Borisova A. , Borisov Y. , Adeeva L. , Tunik A. , Karpets M. , Doroshenko L. 
Published: September 2022

Abstract
Development of thermal spraying of quasicrystalline coatings is connected with development of new powders for produced from alloyed quasicrystalline alloys. Powders of AlCuFe alloyed by Cr and Sc were produced by high – pressure water atomization of melt. Phase composition, microstructure, morphology, flowability of the powders were investigated. Resistance of powders to oxidation in air was studied using thermography. It was determined that doping of AlCuFe – alloy by 0,265 and 0,440 at.% Sc and by 8 at.% Cr significantly increases in them content of quasicrystalline phases. Annealing of AlCuFeCr at 550°C leads to transformation quasicrystalline phase into crystalline approximant of decagonal quasicrystalline phase.
Influence of Process Parameters in the Microstructure and Cavitation Resistance of the Fe-Mn-Cr-Si Metal Cored Wire Developed for Arc Thermal Spraying
Authors: Pukasiewicz A. , Capra A. , Paredes R. 
Published: September 2022

Abstract
The deposition of cavitation-resistant materials coatings in turbine blades is an important way to reduce cavitation damage. Fe-Cr-Mn-Si is a cavitation-resistant steel with many deoxidation elements, which can be important for arc thermal spraying materials. The influence of air pressure, arc tension, and chemical composition on the microstructure, area fraction oxide, porosity, microhardness, and cavitation resistance were studied. Microstructures and properties were investigated by XRD, optical and electronic microscopy, microhardness testing, and ultrasonic cavitation testing per ASTM G32-93. Chromium addition promotes an increase in area fraction oxide, and reduces the porosity, changing the microhardness. An increase in air pressure raised the oxide fraction in the SMA_A and 2 alloys. The SMA_A mass loss rates were 31.8, 25.8, and 37.2 mg/h, respectively, for the samples with 280, 410, and 550 kPa of air pressure. For the SMA_3 samples, the increase in the arc voltage reduces the oxide fraction, changing the mass loss rate to 43.8, 32.4, and 29.4 mg/h for 25, 30, and 35 V, respectively. Phase transformations occurred in the arc thermal spray, for all coatings, during cavitation tests. The SEM analysis verified that the mass loss in arc thermal spray coatings occurred because of the oxide fracture and delamination of the splats.
Study of Copper and Copper-Alumina Cold-Sprayed Deposits
Authors: Rech S. , Trentin A. , Stoyanova V. , Vezzü S. 
Published: September 2022

Abstract
For years, special attention has been paid to study and to develop innovative copper alloys and composites, with improved mechanical behaviour in respect to pure copper and preserving its excellent electrical and thermal properties. In this work different copper/alumina blends have been prepared and then deposited by cold spray at different gas carrier temperatures. The deposition efficiency and the content of embedded alumina have been determined by means of image analysis using SPIP software. Optimized deposition temperature results 450°C: the coatings exhibit compact, pore-free microstructure and very low oxidation. Microhardness and friction coefficient have been evaluated of both pure copper and composite coatings. An increase of microhardness from 65HV0.015 to 150HV0.5 has been observed while a progressive reduction of friction coefficient as a function of alumina content has been reported. Further characterizations to determine thermal and electrical properties of copper/alumina composites are in progress.
Preparation of Multimodal Structured WC-12Co Deposits by Cold Spraying
Authors: Gao P. , Yang G. , Li C. 
Published: September 2022

Abstract
Micro-structural design had attracted increasing interests in modern developments of hard coatings. The ability of cold spray process to retain the feedstock microstructure into coating makes it possible to design coating microstructure through feedstocks for development of different coating properties. In this study, a multi-size modal WC-12Co powder containing nano-sized WC particles was designed to deposit WC-Co deposition with multi-sized WC. Multimodal WC-12Co powders were prepared with ball-milling of a commercial WC-12Co powder, cold-compacting, sintering in hydrogen atmosphere and crushing. WC particle size in the powder exhibits a distribution with two peaks in tens of nanometers and several micrometers. The multimodal WC-12Co deposition was prepared by cold spraying using helium as driving gas. The multimodal size of WC particles in the powders was retained into the deposit. The micro-hardness and fracture toughness of the multimodal structured WC-12Co deposit was compared with bulk WC-12Co. It was found that the multimodal deposition exhibits a comparable hardness to nano-sized WC-12Co and a high fracture toughness compared with micro-sized WC-12Co. The simultaneous strengthening and toughening of WC-12Co can be realized through the bimodal microstructure design of WC-Co.