bluuebunny/crossref_metadata_2025 huggingface dataset:
Flame-Spray Parameter Optimization to Manufacture Glaze Coatings Onto Thermally Sensitive Substrates
Authors: Arcondéguy A. , Montavon G. , Denoirjean A. , Pateyron B. , Grimaud A. , Gasgnier G. , Huguet C. , Planche M.P.
Published: September 2022

Glazes are attractive materials as they can be applied onto metallic or ceramic substrates to confer on them specific properties. They find numerous applications, from art ornamenting to protection against corrosion. Conventional process (vitreous glazing) requires a high temperature treatment (up to 1400 °C in some cases) to fuse glazes after their application on the surface to be covered. This treatment cannot be hence applied onto heat-sensitive substrates without severe degradation. Previous studies showed that manufacturing glaze layers by flame spraying prevents the substrate from thermal degradation. The coating formation mechanisms are different from the ones encountered with crystallized ceramic materials: the high surface tension of glazes prevents the particles from being totally spread (i.e., "dewetting" phenomena). Effects of glaze powder characteristics (chemical composition, particles morphology) on coatings structures were also studied. Furthermore, chemical analyses proved that flame spraying did not modify glaze compositions. The most adapted powder to flame spraying has been hence selected. This contribution describes the coating formation mechanism and discusses the influence of the feedstock powder physical properties on coating characteristics. It also estimates effects of spraying parameters on coatings morphology.
Wear Behaviors of HVAF Sprayed Nano WC-Co Coating Against Al-Ni-Bronze Alloy
Authors: Deng C.M. , Zhou K.S. , Liu M. , Deng C.G. , Hong R.J.
Published: September 2022

High velocity oxygen fuel (HVOF) sprayed WC coatings have been found wide applications as substitutions of chrome plating in the airplane industry. The wear of HVOF WC coated landing gear against Al-Ni-Bronze alloy leads to the wear or spalling of WC particles, and finally results in the degradation of sealing property for landing gear system. WC-Co coating with nano-size WC particles is expected to exhibit good wear resistance, and the weight loss of Al-Ni-Bronze alloy can also be reduced, which is beneficial to the sealing property of landing gear system. Three types of coatings are prepared using agglomerated, sintered nano-scaled WC-12Co, conventional WC- 12Co and WC-10Co4C powders, respectively. The wear behaviors of the as-sprayed coatings against Al-Ni- Bronze alloy are investigated at the different loads and linear velocities. The study is expected to provide the basis for the application of HVO/AF nano-scaled WC coating in landing gear.
High Velocity Oxy-Fuel (HVOF) Suspension Spraying of Mullite Coatings
Authors: Oberste Berghaus J. , Marple B.R.
Published: September 2022

Mullite coatings (3Al2O3 ·2SiO2) were deposited by suspension thermal spraying of micron-sized (D50 = 1.8 µm) feedstock powders, using a high-velocity-oxy-fuel gun (HVOF) operated on propylene (DJ-2700) and hydrogen fuels (DJ-2600). The liquid carrier employed in this approach allows for controlled injection of much finer particles than in conventional thermal spraying, leading to coatings with low porosity and fine and homogeneous porosity distribution, making this process potentially suitable for creating thin layers with low gas permeability. In-flight particle states were measured for a number of spray conditions of varying fuel-to-oxygen ratios and standoff distances and related to the resulting microstructure, stoichiometry, phase composition (EDS, SEM, XRD) and hardness (VHN 300gf) of the coatings. In an attempt to retain the crystalline phase in the coatings, HVOF operating conditions were varied to limit in-flight particle melting. However, fully crystalline coatings were only obtained by gradually heating the coating during deposition to temperatures above 400°C.
Role of HVOF-Spray NiCr Coatings to Control High Temperature Oxidation of Some Boiler Steels
Authors: Kaushal G. , Singh H. , Prakash S.
Published: September 2022

A study was carried out to determine the role of HVOF-spray Ni-20Cr coatings to enhance high temperature oxidation resistance of T22 and 347H boiler steels. Ni-20Cr coatings were deposited on the boiler steels. Subsequently high temperature oxidation behavior of these coatings was investigated by laboratory tests at an elevated temperature of 9000C under cyclic conditions. These coatings were also subjected to a boiler environment at an elevated temperature of 700ºC under cyclic conditions to ascertain their erosion-corrosion behaviour. Thermogravimetric data was taken after each cycle to formulate the oxidation, as well as, erosion-corrosion kinetics. The specimens were also physically examined after each cycle to notice any macrographic physical changes, spallation tendency of their oxide scales etc. The exposed specimens were examined using scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS) analysis. It was observed that oxidation rate was subsequently low in the coated substrates as compare to uncoated steels. It was observed that Ni-20Cr coating on 347H boiler substrate showed the maximum oxidation resistance. Moreover, both the steels showed better resistance to erosion-corrosion in actual boiler conditions after the application of Ni-20Cr coating.
A Numerical Model for Combustion and Expansion in HVOF Flame Spraying
Authors: Dongmo E. , Gadow R. , Wenzelburger M.
Published: September 2022

Nano structured coatings applied by supersonic flame spray processes show a better bonding mechanism, superior hardness and better wear resistance compared to coatings with micron scale structure. However, handling and particle feeding of smaller scale (< 20µm) spray powders is difficult due to their large surface area and easy agglomeration, but also health risks. Therefore, nano structured oxide ceramic powders are mixed with organic solvents in order to form liquid suspensions that are suitable to improve the particle feeding properties. Recent attempts to understand the momentum and heat transfer mechanisms between flame and particles in HVOF flame spraying led to measurement of the in-flight particle properties and computational modeling of the processes. In this work, modeling and simulation of the HVOF spraying process as a two phase model is applied in order to analyze thermal and mass flow processes for an optimization of the spray particle properties and the final properties of the coatings themselves. Simulation results are given for particle tracking during the spray process. Thereby, particle properties are sensitive to a large number of process parameters as well as the particle diameter. Numerical results are validated by experimental diagnosis of particle properties with the SprayWatch system and by the analysis of experimental coatings.
HVAF Coating Application in Steel-Making Process
Authors: Korobov Y. , Filippov M.
Published: September 2022

A significant group of steel-making process parts is exposed to high contact pressure, shock abrasive wear and elevated temperature. High productivity repair techniques are necessary because of the large size of the parts. Analysis of coating metallographic investigations, wear and corrosion test results, full-scale tests shows that restoration of base share of these parts is possible by High Velocity Oxygen Fuel / High Velocity Air Fuel (HVOF/HVAF) process. Comparison of manufacture's data has showed that HVAF excels HVOF alternatives noticeably at productivity. At the same time production costs are 2-2.5 times less. With regard to typical steel-making process parts some investigations results and examples of HVAF restoration at Joint Stock Company "Mashprom" are represented.
Properties of Long Persistent SrAl2O4 Ceramics Coating Deposited by Low Power Plasma Spraying
Authors: Zhou F. , Fu Y. , Gao Y.
Published: September 2022

Strontium aluminates activated by Eu, Dy3+ ions has recently attracted more attention due to not only their bright luminescence and super long afterglow without radioactivity but also the extensive application. SrAl2O4:Eu, Dy coatings were prepared by low power plasma thermal spraying (2.5-4W). The optimum spraying conditions have been established with spray parameters. The effects of the plasma conditions on the porosity rate of the coatings were investigated by many techniques, respectively X-ray diffraction (XRD) and scanning electron microscopy (SEM). To better qualify the characteristics of these coatings prepared from spray-dried powders, luminescence characteristics were also studied.
Comparative Study between Ar-H2 and N2-H2 Plasma Gas Mixtures: Application to ZrO2-Y2O3 Coatings
Authors: Noguès-Delbos E. , Goutier S. , Vardelle M. , Fauchais P. , Granger P.
Published: September 2022

In plasma spray process, ceramic coatings can be sprayed by using either argon-hydrogen or nitrogen-hydrogen plasma gas mixtures. Starting from a given particle size distribution the question is what are the spray parameters allowing achieving similar coatings with these types of plasmas? The problem is made more complex because a torch working with Ar-H2 is different from that using N2-H2 as plasma forming gas. It is thus necessary to compare the gas mixture properties, the torches working conditions (mean voltage and thermal efficiency for given current), the arc column diameter relatively to the nozzle internal diameter and the spray parameters, the arc root fluctuations, the powder injection, the particles mean temperatures and velocities as well as their fluctuations linked to those of arc root, the splat formation, the coating porosity and deposition efficiency. This comparison has been achieved for ZrO2-Y2O3 (7 vol%) powder with a size distribution between 5 and 25 µm and using the same plasma torch for the two plasma gas mixtures: a 3MB torch with a cylindrical anode nozzle and 5.5 mm in internal diameter.
Fluctuations in One-Cathode Plasma Torches: Characterization and Modelling
Authors: Marqués J.-L. , Fuchs M. , Dschung F. , Lange S. , Zierhut J. , Schein J.
Published: September 2022

Increasing erosion of the anode wall of a single-cathode F4 torch changes the fluctuation pattern of the plasma jet. Trajectories and temperature history of particles injected into the plasma become accordingly modified. In this work such fluctuations are characterised through spectral analysis of the torch voltage as well as of the light intensity of the jet outside the torch. Instead of considering the evolution of the main peaks in the frequency spectrum for both voltage and optical signals, the variation with increasing torch wear of the spectrum’s higher frequency fraction (above 20kHz) is focused on. The evolution of the fractal dimension in this high frequency range exhibits a reliable correlation with the erosion of the anode wall. This is confirmed further by the development of a simple stochastic model for the motion of the arc root along the anode wall. This model yields, depending on the probability for a pronounced arc root jump, a fractal dimension and an evolution just within the range observed in the measurements. Additionally, tracking the fluctuations at different locations outside the torch enables the isolation of the fluctuation dissipation due to jet viscosity and velocity.
Processing and Properties of Plasma Sprayed W+Cu Composites
Authors: Matějíček J. , Mušálek R.
Published: September 2022

Tungsten-copper composites and FGMs can find applications in various thermal management systems. One example is plasma facing components for nuclear fusion devices, where tungsten provides the heat-resistant plasma facing armor, copper provides the highly conductive heat sink, while the composite or FGM can reduce the stress concentration at the interface. In this study, W+Cu composites of various compositions were produced by water-stabilized plasma spraying. With the help of in-flight particle and plume diagnostics, the powder injection was optimized for each material, and the feed rates were adjusted to account for different deposition efficiencies. The composition, structure, thermal and mechanical properties of the coatings were characterized.
Atmospheric Plasma Spray Process Control
Authors: Kanta A.-F. , Planche M.-P. , Coddet C. , Montavon G. , Vardelle M. , Berndt C.C.
Published: September 2022

Parametric drifts and fluctuations occur during plasma spraying. These drifts and fluctuations originate primarily from electrode wear and intrinsic plasma jet instabilities. One challenge is to control the manufacturing process by identifying the parameter interdependencies, correlations and individual effects on the in-flight particle characteristics. Such control is needed through methods that (i) consider the interdependencies that influence process variability and that also (ii) quantify the processing parameter-process response relationships. Artificial intelligence is proposed for thermal spray applications. The specific case of predicting plasma power parameters to manufacture grey alumina (Al2O3-TiO2, 13% by wt.) coatings was considered and the influence of the plasma spray process on the in-flight particle characteristics was investigated.
Effect of Feedstock Powder Characteristics on Microstructure and Mechanical Properties of Lanthanum Silicate Coatings Deposited by Atmospheric Plasma Spraying
Authors: Gao W. , Zhang C. , Liao H.L. , Lapostolle F. , Coddet C.
Published: September 2022

Lanthanum silicate coatings were deposited onto stainless steel substrates by atmospheric plasma spraying (APS) using mechanically mixed (type A) and calcined feedstock (type B) powders. The phase composition, microstructure, density and porosity of coatings prepared from the two types of powder were compared.
Modelling of the In-Flight Synthesis of TaC Nanoparticles in Thermal Plasma Jet
Authors: Vorobev A. , Zikanov O. , Mohanty P.
Published: September 2022

A simple and efficient numerical model describing the processes of nucleation, growth, and transport of multicomponent nanoparticles is developed. The approach is similar to the classical method of moments but can be applied to co-condensation of several substances. The processes of homogeneous nucleation, heterogeneous growth, and coagulations due to Brownian collisions are considered in combination with the convective and diffusive transport of particles and reacting gases within multidimensional geometries. The model is applied to the analysis of multi-component co-condensation of TaC nanoparticles within a DC plasma reactor.
The Effect of Process Conditions on the Microstructure and Corrosion Resistance of Cold Sprayed Ti Coatings
Authors: Wang H. , Hou B. , Wang J. , Wang Q.
Published: September 2022

Ti and Ti alloys can be applied to the steels as a protective coating in view of its excellent resistance to corrosive environment. Cold spraying as a new surface engineering technique has potential advantages in Ti coating manufacturing in comparison with conventional thermal spraying techniques. Ti coatings were prepared on a carbon steel substrate by cold spraying via controlling the process condition variables concluding carrying gas, temperature and pressure. The microstructure of coatings was observed by SEM. Potentiodynamic polarization experiments were performed to understand the corrosion behavior of the coatings. The SEM examination showed that the coatings become more compact with increase of molecular weight, pressure and temperature of carrier gas. Potentiodynamic polarization technique was used to measure the corrosion and electrochemical property of coatings deposited under different process conditions and surface conditions. The polarization curves indicated that the coatings which had lower porosity had lower corrosion current. The polishing treatment peeled the rough outer layer including the small pores as well as decreasing of the actual surface area of the coating, leading to the considerable improvement of corrosion resistance.
Corrosion Behavior of In-Situ AI2O3 Formed Composite Coating by DC Plasma Spraying
Authors: Dikici B. , Tekmen C. , Gavgali M. , Tsunekawa Y. , Okumiya M.
Published: September 2022

In-situ plasma spraying (IPS) is a promising process to fabricate composite coatings with in-situ formed thermodynamically stable phases. In the present study, mechanically alloyed Al–12Si and SiO2 powder was deposited onto an aluminum substrate by atmospheric plasma spraying (APS) to obtain a composite coating consist of in-situ formed alumina reinforced hypereutectic Al-18Si matrix alloy. The effect of arc current on the corrosion behavior of the composite coating has been investigated. Corrosion resistance of the composite coatings was analyzed by using the potentiodynamic polarization scanning (PDS) technique. Surface morphology of the coatings before and after the corrosion test was examined by using metallographic methods and scanning electron microscopy (SEM). Obtained results are discussed in detail.
Cladding of Aluminum Substrates with Nano Crystalline Solidifying Wear Resistant Iron-Based Materials
Authors: Wilden J. , Jahn S. , Reich S.
Published: September 2022

Since many years, aluminum alloys are established as lightweight construction materials. To reach a partial wear protection for aluminum components in conjunction with seal faces, inlays, made of wear resistant materials, are commonly used. Problems concerning this approach are the necessary space and the endurance strength of the inlay - part joint. New process equipment offers the potential to control the energy input into the substrate and so the formation of brittle intermetallic phases in the aluminum-steel interface as well as the thermal stresses. The usage of new nano crystalline solidifying wear resistant iron-based feedstock materials with advantageous physical and mechanical properties enables further applications beside the wear protection of surfaces, for example as metallic heat insulation layer with a low heat conductivity, close to the values of ceramics.
Production of High Quality Anti-Corrosion and Wear-Resistant Wire Arc Sprayed Coatings
Authors: Wilden J. , Jahn S. , Reich S.
Published: September 2022

Aim of this project is to produce anti-corrosion coatings for high temperature applications by wire arc spraying. It is necessary to adjust the feedstock material as well as the spray equipment in order to control the coating composition and the coating morphology. The substitution of expensive Ni- and Co-based feedstock by Fe-based alloys leads to an economic benefit. In combination with wire arc spraying, the total coating costs can be reduced significantly. There is also an enomous potential for reduction of service costs in waste incineration plants due to an enhanced coating service life and shorter downtime for the anti-corrosion coating repair.
Structure and Tribological Characteristics of HVOF Coatings Sprayed from Powder Blends of Cr3C2-25NiCr and NiCrBSi Alloy
Authors: Määttä A. , Kanerva U. , Vuoristo P.
Published: September 2022

HVOF spraying was used to prepare coatings from mechanical blends of Cr3C2-25NiCr and NiCrBSi powders. The aim of the work was to study the influence of addition of a metallic phase on tribological properties of the coatings in sliding conditions. Tribological properties of the coatings were characterised under dry sliding. Addition of NiCrBSi decreased the coefficient of friction in high temperature, pressure and sliding speed.
Characterization of High-Temperature Abrasive Wear of Cold-Sprayed FeAl Intermetallic Compound Coating
Authors: Li C.-J. , Wang H.-T. , King G.-J. , Zhao S.-N. , Bao C.-G.
Published: September 2022

FeAl intermetallic compound coating was prepared by cold spraying a mechanically alloyed Fe(Al) alloy powder followed by post-spray annealing at 950°C. The high-temperature abrasive wear test was carried out for the annealed cold-sprayed FeAl at a temperature range from room temperature to 800°C. The high temperature abrasive wear of a heat-resistant stainless steel 2520 was performed for comparison. The results showed that the annealing treatment of the as-sprayed Fe(Al) alloy coating at a temperature of 950°C results in the formation of dense FeAl intermetallic compound coating with no particle boundaries. It was found that with the increase of the test temperature the wear rate of the stainless steel increased at the temperature higher than 400°C, while the wear rate of cold sprayed FeAl coating tended to decrease at the temperature higher than 400°C. The high temperature abrasive wear resistance of the cold-sprayed FeAl intermetallic compound coating increased with the increase of the abrasive wear temperature in a temperature range from 400°C to 600°C and changed little in the temperature range from 600°C up to 800°C. The wear resistance of cold-sprayed FeAl coating was higher than that of heat-resistant 2520 stainless steel under 800°C by a factor of 3.
Plasma Sprayed NiCr Coatings Using a Gas Shroud System
Authors: Morks M. F. , Berndt C. C.
Published: September 2022

The oxidation of a NiCr bond coat during air plasma spraying was controlled by designing a gas shroud system that attached to the plasma torch nozzle. Two nozzles, termed as “normal” and “high speed” nozzles examined the effect of nozzle internal design on the microstructure and phase structure of coatings. X-ray diffraction and SEM morphologies showed that the shroud system reduced the oxidation of NiCr particles during the spray process. Compared with conventional air plasma spraying, the argon gas shroud reduced the coating hardness because the volume fraction of partially melted particles increased. The high speed nozzle reduced the oxidation and hardness of NiCr coatings due to the increase of partially melted particles in the coatings.
Composite Coatings with Drag Reduction and Self-Cleaning Properties
Authors: Wilden J. , Drescher V. E. , Schaaf P. , Günschmann S.
Published: September 2022

Today, the efficiency of turbines is limited by different losses. Minimizing these losses is a main goal to reduce fuel consumption and produce more environmentally friendly machines. Observations on the scales of fast swimming sharks display a riblet structure. These riblets provide a significant reduction of drag losses, but are quite sensitive on pollution. Therefore, for a good performance, it is essential to combine these structures with self-cleaning properties. A lateral- and depth-selective distribution of particles with a negative thermal expansion coefficient (NTE) in a binder with positive thermal expansion coefficient can be used to deform the surfaces depending on the temperature. At high temperatures a riblet structure will be formed by local expansion or shrinkage and at cooling down the surface will be cleaned by the reversal of the deformation. Beside the production of a coating with a lateral- and depth-selective distribution of the NTE-ceramics within the binder the thermodynamical stability of the ceramics inside the binder is part of the investigations to provide a sufficient long-time stability of the coating.
Microstructure and Mechanical Properties of Cold Spray Titanium Coatings
Authors: Gulizia S. , Trentin A. , Vezzù S. , Rech S. , King P. , Jahedi M. , Guagliano M.
Published: September 2022

Titanium and titanium alloy coatings have high potential for applications in several industrial fields such as aerospace, bio-medical and chemical industries. Its eligibility for each single application depends on physical, chemical and mechanical properties. Cold spray as a deposition technique for titanium coating is growing because there is no need for vacuum or protective atmospheres. The properties of cold spray titanium coatings can be tailored by controlling and optimizing the process parameters. In this study the effect of the gas pressure and temperature on the deposition process and the coatings properties were examined. Cold spray CP-titanium coatings were produced using nitrogen as propellant gas at different gas pressures (from 2.0 MPa to 3.5 MPa) and temperatures (from 400°C to 800°C). Morphology and the microstructure of the CP titanium powder and coatings were studied by scanning electron microscope (SEM) and light optical microscope (LOM). Micro-hardness measurements and oxygen and nitrogen contents of titanium powder and the coatings were performed. As a final step, residual stress analysis of deposits were measured by means of X-ray diffraction.
Layer Formation of Cold-Sprayed Ceramic Titanium Dioxide Layers on Metal Surfaces
Authors: Kliemann J.-O. , Gutzmann H. , Gärtner F. , Klassen T. , Jursic I. , Borchers C.
Published: September 2022

In cold spraying, the required heat for bonding is provided by plastic deformation of the impacting ductile particles. Therefore, cold spraying is a well-established method for metal on metal coatings. However, few authors have investigated the impact phenomena and layer formation process for impacting brittle ceramic particles on ductile metal surfaces. For this study, titanium dioxide (TiO2) on metal surfaces was chosen as a model system, and layer formation on aluminum, copper, titanium and steel substrates was investigated by SEM, TEM, XRD and Raman spectroscopy. The results show that the deposition efficiency depends on spray temperature, powder properties, and in particular on substrate ductility, even for an impact of ceramic particles during a second pass over already coated areas. High-resolution TEM images revealed no crystal growth or phase transitions at the ceramic/metal interfaces. Nevertheless, a clear dependence of the photocatalytic activity on spray parameters and substrate material could be observed. Cold-sprayed TiO2-coatings have potential applications in biomedical implants or as photo-catalytic functional systems
Plasma Spraying of Lanthanum Silicate Electrolytes for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs)
Authors: Dru S. , Meillot E. , Wittmann-Teneze K. , Saboungi M.-L. , Benoit R.
Published: September 2022

A new challenge in the field of Solid Oxide Fuel Cells (SOFCs) concerns the reduction of their operating temperature down to 700°C. Apatite ceramics are interesting alternatives for SOFC electrolytes due to their high ionic conductivity at this temperature. The present work reports on the manufacturing and characterization of La9SrSi6O26.5 coatings obtained by atmospheric plasma spraying at two different plasma spray powders. The microstructure and the composition of the as-sprayed and heat-treated coatings were investigated by several techniques including X-Ray Diffraction, Inductively Coupled Plasma - Atomic Emission Spectroscopy as well as Scanning and Transmission Electron Microscopy. The porosity level of the coatings was evaluated by the Archimedean method and image analysis. The studies revealed that the as-sprayed apatite coatings were composed of an amorphous phase, a crystalline apatite phase and chemical heterogeneities due to Si volatilization in the high-temperature plasma. Furthermore, a heat treatment made it possible to obtain denser, fully crystallized apatite coatings and also improved their ionic conductivity.
Education, Training and Certification in Thermal Spraying
Authors: Huber R. , Ohliger-Volmer A. , Zech F.
Published: September 2022

Thermal spraying is a continuously growing technology in the field of surfacing, already established long time in many high-tech-applications. In air craft turbines, in power generating technology or even in printing and paper industry, numerous requirements of the coatings are solved with the help of thermal spraying. To rule such a special process, how it is called in the language of standardization, because the results of such processes can only be proofed by nondestructive methods in a very restricted way, you need to use calibrated and controlled equipment and parameters as well as adequately experienced, trained and qualified personnel. The GTS – Association of Thermal Sprayers e.V. was founded with the aim to meet these problems successfully. On one hand the association should promote the profile of the thermal spraying technology. On the other hand the GTS wanted to define a quality standard for TS companies concerning to its quality management system, the spraying procedures and the personnel. These requirements were completed by international acknowledged EWF-training guidelines for supervising personnel and workers up to now. EN and ISO standards in the field of quality management, applications and testing were also created.
GTS – An Important Regulator for Thermal Spray Technology
Authors: Heinrich P. , Penszior C.
Published: September 2022

Gemeinschaft Thermisches Spritzen e.V. (GTS), the Association of Thermal Sprayers, has built up its excellent reputation and success on a sophisticated and, at the same time, transparent quality assurance network with replicable and comprehensible implementation procedures for thermal spraying. For this reason, along with its thermal spray marketing activities, GTS is deemed an important guarantor for this surface technology. This paper provides an overview of the GTS documents and related GTS workflow and procedures compiled for this purpose. Information on quality assurance provided by GTS papers and by the GTS certificate is also provided. The paper also covers activities and member services associated with GTS.
Thermally Sprayed Fine Fe-Based Materials for Wear Protection Applications in the Printing Industry
Authors: Bobzin K. , Schlaefer T. , Warda T. , Schaefer M.
Published: September 2022

Iron based materials are classified as being more health and environmentally friendly as well as cost-effective (material and machining costs) compared to typical materials used for wear protection applications (e.g. cermets). The advantage which is seen in using very fine powders (< 15 μm), is their potential to spray relatively thin, dense near-net-shape coatings with comparable smooth surfaces. This can lead to lower coating as well as machining costs. In this work fine Fe-based powders (-15+5 μm) have been used in order to produce wear resistant coatings for applications in the printing industry by means of air plasma spraying (APS). With regard to oxidation problems of such fine Fe-based materials a shroud for the air plasma spraying system has been developed and deployed. The resulting coatings have been analysed with respect to the microstructure, micro hardness, chemical and phase composition as well as surface roughness (as-sprayed). The economical aspects have also been considered.
Deposition of TiO2 Ceramic Particles on Cold Spray Process
Authors: Yamada M. , Isago H. , Shima K. , Nakano H. , Fukumoto M.
Published: September 2022

Cold spraying has been developed as a high-quality coating process. However, the deposition materials were limited as metallic materials. In this paper, titanium dioxide (TiO2) ceramic particles are deposited on several substrate materials and formed thick coatings, making this approach suitable for a wide range of photocatalytic applications. In order to understand the adhesion mechanism of solid ceramic particles, the structures of feedstock particles are carefully observed with a scanning electron microscope (SEM) and a high-resolution transmission electron microscope (TEM). We find a porous structure which is agglomerated with nano-scaled primary particles. It is assumed that the break down phenomenon occurs due to the cold spray process and influences the adhesion of ceramic particles. The primary particles are bonded within a single crystal. This particular structure is the main factor to make adhesion between the particle and the substrate. SEM and TEM analysis clearly reveals adhesion mechanisms related to the impact of spraying ceramic particles toward the substrate.
Cavitation Erosion Properties and Fracture Morphology of Thermal Spray Coatings
Authors: Kanno A. , Takabatake T. , Namba Y. , Tani K. , Uematsu S. , Sugasawa S. , Yoshioka M. , Ishihara Y.
Published: September 2022

Damage of marine screw propeller parts made of aluminum bronze cast material caused by cavitation erosion is one of the serious problems. Erosion resistant thermal spray coating on aluminum-bronze material is expected to extend lifetime of such propellers. In this study, Cobalt-based alloy coatings sprayed by; (a) atmospheric plasma spraying (APS), (b) low pressure plasma spraying (LPPS) and (c) high velocity oxy-fuel (HVOF) spraying and aluminum bronze cast material were evaluated by cavitation erosion test using magnetostrictive cavitation test equipment. Fracture morphology of cavitation eroded coating surfaces were analyzed by surface observations with SEM and also the amount of volume loss was measured. Cobalt-based alloy coatings sprayed by LPPS exhibited superior cavitation erosion resistance compared to aluminum bronze cast material and coatings by APS and HVOF. Moreover, mechanical properties of Cobalt-based alloy coatings were investigated in detail by nanoindentation technique. It is found that cavitation erosion resistance of coatings is subjected to interparticle cohesive strength.
The Advancement and Positioning of Laser Cladding in the Surface Engineering Industry
Authors: Marchione T. , Dezert D. , Choong A.
Published: September 2022

During the past 20 years, Technogenia Inc. has imposed laser cladding for the enhancement of wear parts and repairs under the trade name of LASERCARB. In spite of the technical differences and advantages, laser cladding has been perceived as a competitive technology to thermal spraying. However, it has had a slow acceptance in the surface engineering industry. This article is a technical and economical update on LASERCARB. New laser, processed materials, capabilities, performances and trends are presented. Economical approaches include background market analysis, cost analysis and technology cost trend. Finally, a processes comparison eases the positioning technology to each other and highlights supplemental aspects.
The Use of National and EC Public Funds for Financing R&D Activities: The Case of a Thermal Spray Shop
Authors: Meneghetti S. , Giolli C. , Giorgetti A. , Scrivani A.
Published: September 2022

The current critical situation of the world economy pushes the companies to make themselves adaptable and to change their usual rigid behaviour in order to survive globalization of the market and the current financial crisis. A large quantity of people entering into the market created a sudden economic earthquake: the needs of goods and their way of production have changed with a subsequent unbalancing of supply and demand. The so called low cost countries (LCC) can offer a significant amount of goods at extremely low prices, with a high capability to “copy” the non-protected technologies. As consequence, it could be noted a movement of production from the rich western countries to the low cost countries, already established in several sectors (textiles, automotive, consumption goods, etc.) and in progress for higher technology sectors. The possible way to face this problem for European and US companies is to invest and increase the technological level of their products by means of effective Research and Development. This is even more valid for the SMEs. The help of the public bodies in funding R&D is crucial in order to make R&D costs acceptable for companies. This paper addresses the study of the financial instruments available for companies in order to obtain financial help for research and innovation: advantages and disadvantages are discussed. An industrial case study is shown, related to a thermal spray shop dealing with gas turbine components, where the efficient and effective use of research allows the set up and the development of the company and also contributes to the surrounding market.
Portable High Pressure Cold Spray Process – Equipment, Coatings and Applications
Authors: Karthikeyan J. , Kay C. M. , Hoell H.
Published: September 2022

Cold spray produces superior coatings with many unique properties, which have led to many new applications of sprayed coatings. In a few applications, such as in-situ repair of aircraft body/engine parts, etc., a portable system is required. Though some portable low pressure (5 – 10 bars) systems are available, these systems have many limitations on coating materials and coating qualities. Recently a ‘Portable high pressure cold spray system’, called Kinetiks 2000, has been developed. Kinetiks 2000 system can operate at 400 °C max nitrogen temperature and 20 bars max gas pressure. A touch panel on the console is used to input and control the process parameters. A hand held gun with a filament heater and a gun body, mounted directly onto the heater, is used for manual spray. This system operates with two different powder hoppers. Coatings of many materials, including aluminum, copper, titanium, zinc, etc have been produced. Microstructural investigations of sprayed coatings have shown that good, strong, dense coatings with clean interfaces and strong bonding to various substrates can be produced. Experiments are continuing to quantify the process characteristics and record the properties of sprayed coatings.
Influence of Substrate Surface Temperature on the Microstructure and Properties of Plasma-Sprayed Al2O3 Coatings
Authors: Hao S. , Li C.-J. , Yang G.-J. , Xing Y.-Z.
Published: September 2022

Thermally sprayed ceramic coatings have a layered structure with a limited interface bonding. Substrate surface temperature prior to droplets impact during deposition significantly influences the microstructure and properties of the coatings. Through the controlling of substrate surface temperature, the lamellar interface bonding of the deposits could be possibly improved. Al2O3 coatings were deposited by atmospheric plasma spraying at the surface temperatures of 100, 275, 375, 480, 530 and 660°C. The fractured cross-section morphology was characterized by scanning electron microscopy. X-ray diffraction was used to analyse the phase contents. Micro-hardness, Young’s modulus and thermal conductivity of the deposits were measured. It was observed that the interface area with columnar grain growth across splat-splat interfaces was increased with increasing deposition temperature. Consequently, micro-hardness, Young’s modulus and thermal conductivity were increased with the increase of deposition temperature. The improvement of properties suggest that the lamellar interface bonding in the deposits was improved as the substrate surface temperature is increased.
APS-Al2O3 Coatings Versus Arc-Sprayed and Plasma-Anodised Al Layers
Authors: Lampke T. , Meyer D. , Pokhmurska H. , Wielage B.
Published: September 2022

Thermally sprayed alumina coatings are widely used in a range of industrial applications to improve wear and erosion resistance, corrosion protection and thermal insulation of metallic surfaces. These properties are required for many components for production processes in the paper and printing industry. By means of efficient and adjustable coating processes, long-term use of the refined surfaces is obtained. It can be seen that cost-efficient arc-sprayed Al coatings post-treated by plasma-electrolytic oxidation (PEO) form Al2O3-layers with outstanding hardness, bonding strength, abrasion and corrosion resistance as well as extended service time. These coatings are designed to partially replace hard chromium.
Microstructure and Enhanced Mechanical Properties of WC-Co Coatings Obtained by Warm Spraying
Authors: Kuroda S. , Raman G. , Watanabe M. , Komatsu M. , Sato K. , Kitamura J.
Published: September 2022

WC-Co cermet coatings were fabricated by using Warm Spraying, which is a modification of HVOF spraying to lower the temperature of the propellant gas below the melting point of Co. By changing the processing parameters, specimens were prepared for hardness, abrasion wear and particle erosion tests. Their microstructures were examined by SEM and XRD. The microstructure clearly showed the effects of suppression of the dissolution of WC into the Co phase, which is the major cause of embrittlement of the conventional HVOF sprayed WC-Co coatings. By combinations of adequate feedstock powder and processing parameters, it was possible to take advantage of fine WC grain size to prepare coatings with higher hardness (HV > 1400), smoother surface (Ra < 2 μm), and moderately improved wear performances compared with conventional HVOF coatings.
Wire Arc Sprayed Iron-Based Anti-Corrosion Coatings for Waste Incineration Plants
Authors: Wilden J. , Drescher V. , Djahanbakhsh M. , Durham R. , Schütze M.
Published: September 2022

The heat produced by incinerator plants can be used to produce electricity and district heating. Metallic components, e. g. heat exchangers, are exposed to a highly corrosive atmosphere. Gases with particularly high chlorine contents lead to the very quick wear of the base material and define the service time and are the main reason for high maintenance costs. Spraying a corrosion-protective coating on conventional steel gives the possibility to improve the performance of the surface significantly. Due to its easy handling and low operating costs, wire arc spraying has become one of the most established processes. The thermal spray Ni- and Co-based coating alloys are state of the art. The substitution of these materials by Fe-based alloys will lead to a noticeable economic benefit. The latest research activities proved that the addition of silicon raises the corrosion resistance in comparison to FeCr- and NiCr-based alloys. In order to verify the potential of these materials, flux-cored wires with different compositions were manufactured and were applied by means of arc spraying. Subsequently, corrosion investigations were conducted on the specimens in an atmosphere containing chlorine.
Effect of M-CrAlY Coating for Corrosion Resistance in Specific High Temperature Atmosphere
Authors: Niwa A. , Hamashima K.
Published: September 2022

In the glass manufacturing, stainless-steel parts are used in characteristic corrosive reduction atmosphere at high temperature. The reactive products, that are induced by volatilization from the stainless steel surface, cause defects of the glass in this usage. Some thermal spraying coating of thermal-resistant alloys is tested in this study for the protection to the volatilization. It is clarified that, the Ni-Cr-Al-Y film, containing plate-like metal oxide dispersions, shows an outstanding effect as followings; 1) The diffusion rate of Fe from a stainless substrate in this coating film is decreased by the dispersions, and Fe is not detected at surface layer of the coating after a long-term exposure test at high temperature. 2) The reaction between Sn and this coating is not active relatively can, and the further inactivation can be possible by pre-existing heat-treatment in oxidant atmosphere. 3) Both effect (decreasing of Fe diffusion rate and inactivation with Sn) are induced by plate-like Al2O3 particles. These particles are generated by oxidation of Al-content in the coating material.
Improved Hardfacing for Drill Bits and Drilling Tools
Authors: Sue J.A. , Sreshta H. , Qiu B.H.
Published: September 2022

New flame spray hardfacing, DSH (DuraShell Steel Hardfacing, US patent pending), is developed to improve thermal conductivity, abrasion wear and erosion resistance for subterranean drilling application. The hardfacing materials consist of spherical cast WC/W2C and Ni-Si-B alloy powders. The hardfacing compositions are tailored for flame spray and laser cladding processes. Typically, the hardfacing comprises hard spherical cast WC/W2C particles uniformly distributed in a tough Ni-alloy matrix. The hardness of WC/W2C exceeds 2100 Hv.3 and Ni alloy matrix varies from about 400 to 700 Hv.3. High stress and low stress abrasion resistances of these hardfacings were characterized and compared to the conventional cast WC/W2C and Ni-Cr-Si-B-Fe hard coating. The increase in thermal, wear, and erosion resistances of DSH hardfacing improve the durability of PDC steel body bits and drilling tools and their cost effective performance. Several case studies of DSH hardfacings on drill bits are described.
Mathematical Modelling and Simulation of a Kerosene Driven HVOF-Process
Authors: Bobzin K. , Bagcivan N. , Schäfer M.
Published: September 2022

Within the High Velocity Oxygen Fuel Process (HVOF-Process) various fuels can be used to provide the needed thermal and kinetic energy such as ethene, propane, methane or kerosene. Modelling the combustion in a HVOF-System poses a challenge concerning chemical kinetics of the kerosene reaction process. In this work a reduced reaction mechanism and a model describing chemical reactions as well as governing fluid dynamics are presented to simulate kerosene driven HVOF-Process. The kerosene combustion process within a HVOF-System usually takes place above temperatures of 2000 K, where some species dissociate. Therefore, accruing species have to be included in the reaction mechanism. The combustion process is described with a reduced reaction mechanism. The reaction rate is described by a finite rate model in form of Arrhenius. The gas flow is considered as a first phase and the kerosene droplets injected into the combustion chamber become a second phase. Afterwards simulation results are presented and discussed.
Flattening and Cooling of Millimeter- and Micrometer-Sized Alumina Drops
Authors: Goutier S. , Vardelle M. , Labbe J.C. , Fauchais P.
Published: September 2022

An experimental set-up has been developed, at the SPCTS Laboratory, to produce fully melted, millimeter-sized, ceramic or metallic drops with impact velocities up to 10 m/s. Such impact velocities allow reaching impact Weber numbers, close to those of the plasma spray process (We = 2300). A fast camera (4000 image/s) combined to a fast pyrometer (4000 Hz), allows following the drop flattening. For studding the flattening at the micrometer scale, a DC plasma torch is used to melt micrometer sized alumina particles (around 45 μm). The experimental set-up is composed of a fast (50 ns) two-color pyrometer and two fast CCD cameras (one orthogonal and other tangential to the substrate). The flattening of millimeter and micrometer sized particles is compared. First are studied impacts of alumina drops (millimeter sized) with impact velocities up to 10 m/s. Then are considered micrometer sized alumina particles (about 45 μm in diameter) sprayed with a DC plasma torch. A correlation has been found between both flattening scales and, in spite of the lower impact velocity at the millimeter scale, ejections are also found at the micrometer scales. This work shows that to compare phenomena at the two different scales it is mandatory to have Weber numbers as close as possible in both cases.
Effect of Annealing on Microstructure of Cold Sprayed C-BNp/NiCrAl Composite Coating
Authors: Luo X.-T. , Li C.-J. , Yang G.-J.
Published: September 2022

C-BNp/NiCrAl composite coating was deposited by cold spraying using a mechanically alloyed composite powder. To modify coating microstructure, especially the bonding at the interfaces between c-BN particles and NiCrAl alloy matrix, and bonding at the sprayed particle/particle interface, annealing treatment at series of temperatures in Ar atmosphere was carried out. The results show that a zigzag interface layer is formed at the interface between c-BN particle and NiCrAl matrix after annealing at 825°C for 300 min through reaction of c-BN with NiCrAl. It is also observed that the thickness of the interface reaction layer increases with the increasing annealing temperature. Moreover, the interface between spray particles and the plastic deformation ability of the cermet coating can be improved through post-spray annealing. Vickers microhardness test shows that the hardness decreases with increasing annealing temperature due to the reduction of work hardening effect and grain growth of NiCrAl alloy matrix resulting from recovery and recrystallization during annealing treatment.