bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Microstructure and Properties of Thermal-Sprayed Cermet Coatings Modified by Laser Remelting Post-Treatment
Authors: Yin Z. J. , Tan X. H. , Wang Q. X. , Xu S. H. , Hao R. L. , Deng Q. L. , Sun J. S. 
Published: November 2022

Abstract
In this study, carbide-based cermet (WC-Co, WC-NiCr, Cr3C2-NiCr) coatings were prepared by thermal spraying and efforts were made to explore the laser remelting effects on the coating microstructure, hardness, adhesion and tribological behavior under different conditions. Results obtained showed that under elected remelting parameters, laser-treated coatings exhibit denser structures and improved microhardness with smaller variability, as well as enhanced adhesion strength between coating and substrate arising from metallurgical element diffusion. In dry sling condition, HVOF sprayed WC-Co coating after laser remelting showed superior wear resistance, however, contrary to the lubricated condition, which may attribute to more lubricant stored in as-sprayed coatings with higher porosity. Solid particle erosion tests suggested that anti-erosion property of plasma sprayed Cr3C2-NiCr coating by laser remelting are increased, regardless of erosion velocity and angle. Additionally, the wear loss of laser-treated coating increased with erosion velocity, but due to its improved ductility shows no obvious relation to the erosion angle changing from 30 to 90 degree, which is accordance with the wear surface observation and tribological mechanism analysis.
Performance of HVOF and Cold Sprayed Ni-20Cr Coatings in Aggressive Molten Salt Environment at 900°C under Cyclic Condition
Authors: Bala N. , Singh H. , Prakash S. 
Published: November 2022

Abstract
Nickel-chromium alloys have been used as coatings to deal with oxidation environments at high temperature. The present work is a comparative study of HVOF and cold sprayed Ni-20Cr coating on a boiler steel (SAE 213-T22) in a molten salt environment of Na2SO4-60%V2O5 at 900°C under cyclic conditions. The weight change technique was used to establish the kinetics of corrosion. X-ray diffraction, surface and cross-sectional FE-SEM/EDS techniques were used to analyse the corrosion products. The hot corrosion resistance of both the coatings was better than the uncoated steel. This may be attributed to the formation of oxides and spinels of nickel and chromium in the coated steels. These oxides might have blocked the pores and splat boundaries, and acted as diffusion barriers to the inward diffusion of corroding species. Based upon the overall results and subsequent analysis of hot-corrosion data the cold spray process may be recommended as a better choice for the deposition of the Ni-20Cr coating on Mo-containing T22 steel in comparison with the HVOF spray process for hot corrosion protection.
Effect of the Substrate Temperature on Properties and Dissolution of Plasma Sprayed Wollastonite Coatings
Authors: Wang W. Z. , Liang J. C. , Xuan F. Z. 
Published: November 2022

Abstract
Wollastonite coatings were deposited on Ti6Al4V substrate at the substrate temperatures of room temperature, 200 °C, 400 °C and 600 °C by the atmosphere plasma spraying, respectively. The effect of substrate temperature on the microstructure, phase composition, mechanical properties and dissolution behavior of wollastonite coatings were investigated. The microstructure and phase composition of coatings were examined by SEM and XRD. The hardness and elastic modulus were obtained by the Knoop indentation tests. In addition, the dissolution behavior of coatings was evaluated by immersion in SBF solution. The results indicate that a slight decrement of porosity and an obvious increment of crystallinity were found with the substrate temperature. The hardness and elastic modulus of coatings increased with the substrate temperature up to 400 °C firstly, and then a decrement was observed with the temperature further increasing to 600 °C. The dissolution rate of coatings characterized by the pH changes and the released Ca, Si and P concentration in the SBF decrease with the substrate temperature, which is related to the porosity and crystallinity of coatings. It is revealed that through increasing the substrate temperature during plasma spraying is a feasible method to improve the mechanical properties and to decrease the dissolution of wollastonite coatings.
Excimer Laser Surface Treatment of Plasma Sprayed Coatings
Authors: Ibrahim A. , Shahrabi K. , Zoghi M. , Hung Y. , Ryu Y. , Berndt C. C. , Khonsari M. 
Published: November 2022

Abstract
Excimer laser annealing provides a rapid and efficient means for surface alloying and modification of ceramic materials. In this study, Alumina-13% Titania coatings were sprayed with a water-stabilized plasma spray gun. The coated surface was treated by Excimer laser having a wavelength of 248 nm and pulse duration of 24 ns. The surface structure of the treated coating was examined by field emission scanning electron microscope and X-ray diffraction (XRD). A detailed analysis of the effects of various laser parameters including laser energy density (fluence), pulse repetition rate (PRR), and number of pulses on the morphology and the microstructure of the coatings are presented.
Local Corrosion Protection of Joints by Low Pressure Cold Spray
Authors: Dzhurinskiy D. , Maeva E. , Leshchynsky V. , Maev R. Gr. 
Published: November 2022

Abstract
The study of corrosion protection of magnesium and aluminum becomes increasingly important as the use of these alloys increases rapidly in the automotive and aerospace industries due to their advantages of light-weight, adequate mechanical properties and moderate cost. Corrosion, however, limits the application of magnesium and aluminum alloys. Fasteners, spot welds of dissimilar materials and their galvanic corrosion is of major concern in automotive applications. The paper presents first results of Low Pressure Cold Spray (LPCS) of Al based coatings for corrosion protection. The corrosion protection provided by these coatings was evaluated by electrochemical measurements in 1M NaCl electrolyte. The microstructures and electrochemical behavior of the coated joints were investigated. The electrochemical corrosion mechanisms of the coatings and microstructure were discussed.
Computational Analysis of Composite Powders Impacts to Evaluate Ceramic Coatings in Cold Spraying
Authors: Canales H. , Dolmatov A. , Markovich S. 
Published: November 2022

Abstract
Cold Spraying, as a novel Thermal Spraying Technology can deposit a wide range of ductile materials on different substrates; a problem arises when the objective is to use this technology to deposit brittle materials such as ceramics in applications where melting must be avoided. One example is when spraying Bio-Ceramics, in which particle´s melting often leads to changes in physical and chemical properties and subsequently resulting in unknown variations in the coating´s biocompatibility. While Non-Ductile Materials can only be deposited if they are co-cold-sprayed with a ductile (matrix) material a Metal-Ceramic Powder Composite must be used for these objectives. The goal of this paper is to show a transient Non-Linear Dynamics Computational Analysis of a Metal- Ceramic Powders Composite impacting a metallic substrate by the means of Cold Spraying Technology; all this in order to understand the formation of cold sprayed composite coatings while comparing them with experimental results and using ANSYS-AUTODYN© to assess the suitability of this spraying technology for coating special application substrates.
Thermal Spraying of Advanced Zinc Alloys as an Addition to Hot-Dip Galvanizing
Authors: Bobzin K. , Schläfer T. , Warda T. , Schulz C. 
Published: November 2022

Abstract
Zinc coatings are widely adopted for cathodic corrosion protection. Mostly the process of choice is hot-dip galvanizing but due to limitations regarding component size and composition of the galvanizing bath it is not always practicable. In the present paper zinc coatings alloyed with Al, Sn, Mg and Cr are applied by twin wire arc spraying to enhance the corrosion protection ability of zinc thermal sprayed coatings. The alloys were characterized and investigated using salt spray test and by means of electrochemical corrosion. Corrosion damage and products were investigated by optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and electron probe microanalysis (EPMA).
Correlation of the Particle Behavior, Microstructure and Phase Evolution During the Optimization of HVOF Sprayed WC-12Co Coatings by Means of DoE
Authors: Tillmann W. , Hagen L. , Baumann I. , Tolan M. , Paulus M. , Wieland F. 
Published: November 2022

Abstract
Due to their outstanding properties, WC-Co cermet coatings are widely used in the field of wear protection. It has been reported by many researchers, that their macroscopic and tribological behavior is largely determined by the process conditions and the feedstock powder characteristics respectively. Although the manufacturing route for high velocity oxy fuel(HVOF)flame sprayed WC-Co coating is in an advanced state, there is still a lack of knowledge about the complex relationships between the thermo-kinetic in-flight particle behavior, the microstructure formation and the phase evolution during the spray process. However, a fundamental understanding is not only necessary to provide coatings with optimized properties, but also to meet economic aspects with regard to the HVOF process. In this study the dependencies between the HVOF process parameters and characteristics (chamber pressure, thermal energy transferred to the coolant), the thermo-kinetic in-flight particle behavior (temperature, velocity and the spray particle size) with the microstructure formation (carbide content and size, free mean path of the binder phase, porosity), thermal phase reactions and the mechanical properties (hardness, toughness, roughness) were investigated. Statistical design of experiments (DoE) is utilized to enable a systematic analysis of several influencing factors along with their interactions on the coatings properties and to find optimized spray conditions. X-ray diffraction (XRD) applying high-energy synchrotron radiation has been used, not only to provide a phase analysis in deeper regions of the coating structure, but also to achieve more detailed information on phases which are not or hardly detectable by XRD using a conventional X-ray laboratory source. In addition the sliding and abrasive wear properties at optimized coating properties are studied.
Failure Mechanism of Non-Stoichiometric Mg-Al-Spinel Abradable Coatings under Thermal Cyclic Loading
Authors: Ebert S. , Steinke T. , Vaßen R. , Stöver D. 
Published: November 2022

Abstract
Plasma-sprayed ceramic coatings are often used as thermal barrier or abradable coatings in high-pressure stages of gas turbines. They are exposed to high thermo-mechanical loadings, due to the harsh operating conditions. Today, a material typically used in engines as thermal barrier coating material is yttria-stabilised zirconia (YSZ). This material has a low conductivity and a high thermal expansion coefficient, but a limited temperature capability of about 1200°C in long-term applications. For the use as abradable coatings, thicker coatings with a thickness above one millimetre are necessary. However with increasing coating thickness and limited cooling efficiency there is a risk of premature failure. As a result new ceramic materials have been developed. For the lifetime analysis they were tested by thermal gradient cycling tests. In the present work an APS ceramic double-layer topcoat composed of 7YSZ and a top layer of non-stoichiometric magnesia alumina spinel (Mg-Al-Spinel) was used. The layer was sprayed on disc-shaped IN738 superalloy substrates which were coated with a VPS bondcoat. Under specific thermal cycling conditions with temperatures above 1400°C, these samples showed a typical failure mechanism with exfoliation of thin coating lamellae, starting from the coating surface. This failure mechanism was analysed in detail, e.g. by scanning electron microscopy (SEM), X-ray diffraction, and chemical analysis. From these findings, a description of the failure mechanism was developed.
Development of Particle-Reinforced Nanostructured Iron-Based Composite Alloys for Thermal Spraying
Authors: Wielage B. , Lampke T. , Pokhmurska H. , Rupprecht C. , Drehmann R. 
Published: November 2022

Abstract
Cermets like WC/Co or Cr3C2/Ni20Cr are well-established materials for thermally sprayed wear protection coatings. However, their high price and the adverse health effects of nickel and cobalt cause the motivation for the development of novel materials with excellent wear resistance. Within the AiF/DFG research cluster “Thermal Spraying”, a multi-institutional cooperation of various German research centres, the focus is put on particle-reinforced iron-based composite alloys. High-alloyed steels serve as matrix materials into which hard CrB2 particles are incorporated by means of high-energy ball milling (HEM). By adjusting appropriate milling parameters, the microstructure of the powder and its level of amorphisation can be influenced effectively. The high-velocity oxygen fuel process (HVOF) allows a transfer of the desired nanocrystalline structure from the particles to the coatings. The deposited coatings exhibit low porosity and high microhardness values of more than 1000 HV0.3. The wear resistance of the coatings was determined by means of Miller test (ASTM G75-01) and compared with conventional wear protection materials and coatings produced with agglomerated and sintered powders. The obtained outstanding results qualify particle-reinforced iron-based materials as a promising alternative for a wide range of applications.
Development of Ceramic Heating Elements Produced by Thermal Spray Technology
Authors: Toma F.-L. , Scheitz S. , Puschmann R. , Berger L.-M. , Sauchuk V. , Kusnezoff M. 
Published: November 2022

Abstract
In this work, completely ceramic heating elements have been developed by the combination of conductive and insulating thermally sprayed oxide coatings. These heating elements with a total thickness of less than 1 mm have been directly applied on metallic substrates. APS- and HVOF-sprayed Al2O3 and spinel (MgAl2O4) coatings were employed for insulation. A comparative analysis of the insulating properties (dielectric strength, electrical resistivity) of these coatings is presented. The HVOF-sprayed spinel coatings show better dielectric breakdown strength and higher electrical resistance stability. TiOx, TiO2-10%Cr2O3 and TiO2-20%Cr2O3 powders have been used to prepare the electrical conductive coatings. The thermal and oxidation stabilities at high temperature, as well the electrical properties have been investigated. Addition of Cr2O3 reduced the oxidation rate of titanium oxide and increased the operational temperature of the heating coating. A ceramic heater consisting of spinel coating as insulator and TiO2- 20Cr2O3 as conductor was sprayed on a metallic roller and the electrical stability during the long-term (300h) thermo-cycling (from RT to 300°C) was successfully tested.
Thermal Barrier Coatings for Rocket Engines
Authors: Schloesser J. , Bäker M. , Rösler J. 
Published: November 2022

Abstract
In rocket engine combustion chambers the cooling channels are subjected to extremely high temperatures and environmental attack. Because of the good heat conduction the inner combustion liner is made of copper. Thermal and environmental protection can be provided by Thermal Barrier Coating Systems. The performance of an APS-sprayed standard coating system for nickel based substrates (NiCrAlY and YPSZ) on copper substrates is investigated. Because mechanical and thermal properties (e.g. the coefficients of thermal expansion) of the two substrates are different, known failure mechanisms for nickel based substrates can not be directly transferred to the new application. Thermal cycling and laser shock testing is performed to identify possible failure mechanisms. The laser shock setup consists of a high-power diode laser (3kW) and realizes surface temperatures of up to 1500°C. Furthermore, it is possible to realize high thermal gradients inside the specimen, similar to those in real service. Delamination of the thermal barrier coating at the interface between bond coat and substrate is observed. Usually, this interface is not failing in standard applications, which gives an important hint for further research. Furthermore, FEM analysis confirms that stresses are maximal at this interface.
Effect of Bond Coat Material and Heat Treatment on Adhesion Strength and Characteristics of Thermal Barrier Coating System with CGDS, HVOF and APS Techniques
Authors: Lampke T. , El-Mahallawy N. , Grund T. , El-Araby I. , Karaoglanli A. C. 
Published: November 2022

Abstract
The most recent increase in turbine entry temperature (TET) can be obtained by the use of Thermal Barrier Coatings (TBCs) on cooled hot section components. The TBC systems are comprised of Ni-based super-alloy substrate which provides certain mechanical properties and blade geometry consisting of a ceramic top coat with low thermal conductivity applied to a metallic bond coat resulting in a significant temperature drop across the coating. The bond coat provides oxidation resistance and adherence of the top coat to the substrate. In this study different bond coat layers were applied on carbon steel substrates which were covered by yttria stabilized zirconia (YSZ) as a top coat layer using atmospheric plasma spray technique (APS). Al-12%Si and Al 99% were deposited by cold gas dynamic spray technique (CGDS) while Ni-5%Al layer was deposited by high velocity oxy fuel technique (HVOF). Heat treatment was performed on the samples under controlled atmosphere for 15 hrs. The microstructure and micro hardness of as sprayed and after heat treatment samples were investigated. Adhesion strength for top coat / bond coat interface and bond coat / substrate interface were investigated. The residual stresses for as sprayed and after heat treatment was estimated by XRD measurement on the top coat layer with different bond coat material. The results indicate that the adhesion strength either for as sprayed or after heat treatment was enhanced using this new bond coat materials compared to the traditionally as deposited Ni Co Cr Al Y bond coat material.
Preparation and Thermophysical Properties of La2(Zr0.7Ce0.3)2O7 Ceramic Material
Authors: Xiang J. Y. , Chen S. H. , Huang J. H. , Zhou G. D. , Liang W. J. , Wang R. J. , He Q. 
Published: November 2022

Abstract
La2(Zr0.7Ce0.3)2O7(LZ7C3) ceramic was prepared by solid state reaction method at 1400 °C for 12h using La2O3, ZrO2, and CeO2 as starting reactants. The phase composition and microstructures were studied by XRD and SEM technology. The thermal conductivity and linear thermal expansion coefficient were investigated by laser-flash method and pushing-rod method respectively. XRD results revealed that LZ7C3 is a mixture of pyrochlore and fluorite, and the pyrochlore is the main phase which is a small solid solution of La2Ce2O7 (LC) in La2Zr2O7 (LZ). The thermal conductivity of LZ7C3 decrease gradually with the increase in temperature until 1200°C, and the value is 0.79 W⋅m-1⋅K-1, which is almost 50% lower than that of LZ. The linear thermal expansion coefficient which is 11.6 × 10-6 K-1 at 1200°C is larger than that of LZ. These results show that LZ7C3 ceramic material can be explored as a novel prospective candidate material for use in new thermal barrier coating systems in the future.
Study of Plasma Sprayed Mullite Coating Using Mullite and a Mixture of Alumina and Silica Powder Particles
Authors: Salimi Jazi H. , Hosseini M. , Shafyei A. , Samadi H. , Pershin L. , Coyle T. W. , Mostaghimi J. 
Published: November 2022

Abstract
Plasma sprayed ceramic coatings are widely used for thermal barrier coating applications. Commercially available mullite powder particles and a mixture of mechanically alloyed alumina and silica powder particles were used to deposit mullite ceramic coatings by plasma spraying. Microstructure and morphology of both powder particles as well as coatings were investigated by using scanning electron microscopy (SEM). Phase formation and degree of crystallization of coatings were analyzed and estimated by using X-ray diffraction technique. Differential thermal analysis (DTA) method was used to study the phase transformation of coatings. Results indicated that the porosity level in the coating deposited using mullite as initial powder particles was lower than that deposited using the mixed powder particles. The crystallization degree of the coating deposited using the mixed powder particles are higher than that deposited using mullite powder particles. DTA curves of coatings deposited using the mixed powders have showed some phase transformation due to the crystallization of the retained amorphous phases such as mullite and alumina in the coatings. The degree of crystallization of both as sprayed coatings was significantly increased after post deposition heat treatments.
Optimization of Plasma Spray Processing Parameters for Deposition of YSZ+Al2O3 Coating
Authors: Altuncu E. , Tozkoparan D. , Okumus S. C. , Ustel F. 
Published: November 2022

Abstract
Plasma sprayed yttria stabilized zirconia (YSZ) coatings are being increasingly used as thermal barrier coatings(TBCs) for gas turbine parts. However oxidation problems are critical for durability of TBC. Al2O3 addition to YSZ is considered as an oxygen barrier microstructure at elevated temperature. Therefore it helps to the growth rate of the thermally grown oxide layer between top coat and bond coat. Spray properties and rapid solidification determine the final characteristics of the coating. Plasma current, plasma gas flow rate and spray distance factors have main effect on occurrence of microstructure. Therefore plasma spray parameter optimisation is required for TBC manufacturing. Statistical designs of experiments have been shown to provide efficient approaches to systematically investigate the process parameters of plasma spray process. In this study Al2O3-YSZ particle composite TBC deposited with different plasma spray process parameters by using Taguchi method for optimisation.
Effect of the Grit Blasting Exposure Time on the Adhesion of Al2O3 and 316L Coatings
Authors: Vilemova M. , Siegl J. , Matejicek J. , Musalek R. 
Published: November 2022

Abstract
The effect of grit blasting exposure time on the adhesion of plasma sprayed Al2O3 and 316L stainless steel coatings was studied in the present work. The steel substrates were grit blasted prior to the coating deposition. Two sets of substrates with exposure time of 1 and 4 seconds were prepared. Both types of coatings were deposited using Water Stabilized Plasma (WSP) torch. Adhesion strength was evaluated using standardized pulloff test. The obtained results showed a slight improvement in the adhesion strength for the blasting time of 4 s. Failure processes taking place in the coatings during the pull-off tests were described based on the detailed fractographic analysis.
Cold Spray Ultrasonic Monitoring and Modeling
Authors: Maev R. Gr. , Titov S. , Dech J. , Leshchynsky V. 
Published: November 2022

Abstract
To fully understand particle interactions with both substrate and neighboring particles in Cold Spray (CS), ultrasonic monitoring and acoustic emission of particle agglomerate impact were studied. The results obtained show the influence of particle agglomeration density on stress and strain distribution in the particles and at the particle interfaces. The results are compared with metallographic structures of real coatings. The development of monitoring procedure is made using acoustic methods, specifically testing during the actual spray process itself. It is shown that the final thickness as well as the dynamics of buildup can be evaluated. Cross sections of the coating thickness are also easy to obtain and show true profiles of the coating. Comparisons of real thickness and acoustically estimated thickness show a close linear relationship.