bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal Dynamics of Rice Production and Import in Nepal
Authors: Gairhe Samaya , Gauchan Devendra , Timsina Krishna Prasad 
Published: May 2021

Rice is a principal food crop for ensuring national food security and improving the livelihoods of the people in Nepal. To understand and analyse temporal dynamics of rice production and import, a study was carried out by using secondary data during the period from 2009 to 2018. The objectives of the study were to analyses temporal changes and dynamics of rice production and import in Nepal. The study used Compound growth rate and Markov chain analysis to assess the pattern of temporal changes in production and import of rice in Nepal for the last one decade. The synthesis of the analysis is presented in both tabular and graphic forms. The results revealed that Nepal is importing rice in increasing trend and not being able to meet national demands despite some increase in rice production and productivity in the last decade. Imports of rice were found in four harmonized system codes from 18 countries and the value of rice import is mounting in recent years. In addition, Compound growth rate analysis showed that the rice import quantity and value were increasing at the rate of 24.48 and 38.11 percent per annum respectively, while production growth was hovering below less than 2% per annum. The higher growth rate of value than quantity showed that mainly import is concentrated on fine and aromatic rice. Further, the study also reveals the direction of trade using Markov chain analysis, which shows that among selected countries, two countries India and the USA were more stable rice exporters to Nepal while China, Thailand, and Italy were less stable. The study implies that import substitution can be done by increasing productivity with increase use of high yielding hybrids and fine and aromatic rice.
Tungsten Coatings for Nuclear Fusion Devices
Authors: Malléner W. , Hohenauer W. , Stöver D. 
Published: May 2021

Abstract
High-Z materials such as tungsten are currently considered more suitable for the inner coatings of fusion devices than low-Z materials. The VPS parameters are being optimized for different tungsten powders with respect to uniform pore distribution and distribution of unmelted particles in the coating. High process reliability is aimed at in coating production. Copper is used as the substrate material. The spray efficiencies, coating porosities and unmelted particles in the coatings are being examined and the microstructures evaluated. Spraying parameters are determined for two different powder fractions leading to relative densities ≥ 90 % of the theoretical density.
Vacuum Plasma Spray Forming of Tungsten Base Functionally Gradient Composites
Authors: Kim M.R. , Smith R.W. , Kapoor D. 
Published: May 2021

Abstract
Functionally gradient composites were spray formed via vacuum plasma spray deposition using tungsten cylindrical substrates. Materials deposited included tungsten-hafnium alloys and M-2 tool steel. Some deposits included micro-laminate layering with hafiiium alloys sprayed within the tungsten-hafnium matrix. Vacuum plasma deposition was shown to provide a viable means of producing functionally gradient composites from tungsten base materials. This was determined both by microstructural characterization of deposit structures and by measuring the compressive properties of the materials. Compression testing of the W-Hf matrix composites demonstrated compression strength of 1,552 MPa (225 ksi). Compression strengths of the tungsten/steel composite averaged 1,068 MPa (155 ksi). Failure of the W-Hf samples occurred via fracture of the tungsten/hafnium matrix whereas the tungsten/steel composites failed within the wrought tungsten core.
A Study on Thermal Spray Coatings of Recuperators
Authors: Seong B.G. , Hwang S.Y. 
Published: May 2021

Abstract
High temperature corrosion is a serious problem on tlie heat exchanger tubes of recuperators because they encounter an corrosive environment at maximum temperature around 900°C. These tubes were found to be corroded via oxidation, sulfidation and molten salt corrosion. Particularly molten salt corrosion could be the most severe corrosion mechanism. As a protective coating for recuperators, nickel and cobalt based self-fluxing alloys, iron based amorphous alloy and chromium carbide cermet coatings were considered. These coatings were prepared by an arc spray and or/not fusing or a HVOF spray. Their molten salt corrosion resistance was tested, and the high temperature corrosion resistance in a SO2 containing atmosphere was examined. Also microstructures of the coatings were studied after corrosion tests.
The Effect of Spraying Conditions on the Corrosion Resistance of Titanium Coatings for Surgical Implants
Authors: Normand B. , Renaud F. , Coddet C. , Tourenne F. 
Published: May 2021

Abstract
One cause of aseptic loosening of total hip replacement (THR) results from the hard polymetylmethacrylate (PMMA) bone cement debris embedded within some of acetabular cups [1]. To prevent this failure, PMMA can be replaced by a titanium coating with a specific roughness to promote the bone bonding. In this work, inert and atmospheric plasma spraying was used to coat Ti.6A1.4V implants with titanium.] In order to evaluate the effect of the deposition process on the coating corrosion resistance, different electrochemical techniques were implemented in physiological (i. e., Ringer) and in acidic solutions. Results show that the spraying parameters and the coating morphology affect the corrosion behaviour. Thus, if the reactivity is not affected by the pH evolution, the pitting sensitivity depends on the process. It was found that coatings deposited under inert gas are free of oxides and dense, even when the atmosphere contains some hydrogen. In that case a significant improvement of the intrinsic localized corrosion resistance is observed versus deposits obtained using atmospheric plasma spraying.
Microstructure and Properties of WC-CO-Cr Coatings
Authors: Berger L.-M. , Vuoristo P. , Mäntylä T. , Kunert W. , Lengauer W. , Ettmayer P. 
Published: May 2021

Abstract
WC-Co-Cr represents an important composition for hardmetal-like coatings which is appHed when simuhaneous wear and corrosion resistance is required. In this paper five commercially available spray powders obtained by various production techniques (sintered and crushed as well as agglomerated and plasma-densified) of the composition WC-10%Co- 4%Cr have been thoroughly characterized and were sprayed by DCS, HVOF (CDS process) and APS. The microstructures of the coatings were characterized and their wear behaviour was investigated by means of an abrasion wear test. For the best of these powders the wear resistance was nearly equal for the DGS and HVOF coatings. Other powders show significant differences with respect to their processabilities in these spray processes. APS coatings from all powders, obtained with an Ar/H2 plasma showed inferior microstructures and significant lower wear resistance. The spray powder compositions, grain sizes and structures were found to determine the processability of the powders and the microstructure and properties of the coatings. COMPOSITE MATERIALS of the type hard phase - metallic binder with WC and CoCr as constituents are widely used for the preparation of hardmetal-like coatings. The chromium addition to the metallic binder is thought to improve its corrosion resistance in comparison with pure WC-Co. This has led to many applications of WC-CoCr coatings where simultaneous wear and corrosion resistance is required. Despite of its significant practical importance only a limited number of publications is devoted to detailed questions of structure and properties of WC-CoCr coatings (1-3). In some comparative studies such coatings have been investigated together with WC-Co and Cr3C2-NiCr coatings (4-8). However, systematic investigations of spray powder compositions and morphologies as well as investigations of the influence of different thermal spray processes on coating structures and properties which have repeatedly been provided for WC-Co (for example (9, 10)) are missing for WC-CoCr. In this paper a short survey of literature on the phase relationships in the WC-CoCr system and the effect of chromium additions on the properties of sintered parts and thermally sprayed coatings compared to WC-Co is given. In the experimental part a systematic study of the influence of the preparation process on composition and morphology of commercially available WC-10%Co-4%Cr spray powders was provided. These powders have been sprayed by DGS, HVOF and APS and the microstructure and basic properties of the coatings have been studied.
Characterization of WC-Co Coatings Using HP/HVOF Process
Authors: Hwang S.Y. , Seong B.G. , Kim M.C. 
Published: May 2021

Abstract
To maintain surface roughness of process rolls in cold rolling steel plants, WC-Co coatings have been known to be effective ones. In this study, a high pressure/high velocity oxygen fuel (HP/HVOF) process was used to obtain WC-Co coatings. To get the best quality of coatings, WC-Co coatings are sprayed with numerous powders made by various processes. These powders include agglomerated sintered powders, fused-crushed powders, extra high carbon WC-Co powders and (W2C, WC)-Co powders. After spraying, properties of coatings such as hardness, wear resistance. X-ray diffraction, and microstructures were analyzed. For coatings produced by agglomerated-sintered powders, hardness of the coating increased as power levels and the number of passes were increased. In case of the coatings produced by fused-crushed powders, a very low deposition rate was obtained due to a low flowablity of the powders. In addition, the WC-Co coatings sprayed with extra carbon content of WC-Co did not show improved hardness and wear resistance. Also, some decomposition of WC was observed in the coating. Finally, the coatings produced by (W2C, WC)-Co powders produced higher hardness and lower wear resistance coating.
The Utilization of Acetylene and Acetylene Based Gas Mixtures for the HVOF Coating of Chromium Oxide
Authors: Cole M. , Creffield G. 
Published: May 2021

Abstract
Chromium oxide coatings are currently produced predominantly by the plasma spray process utilizing the high process temperatures required to fully soften the high melting point chromium oxide powder. The development of the HVOF process, combining the relatively high flame temperatures of hydrogen, propylene or propane fuel gases with the notably high particle velocities generated by the process, is known to produces dense, low porosity coatings. By utilizing acetylene, the highest flame temperature fuel gas commercially available, and acetylene based mixtures, the HVOF process can be used to successfully spray chromium oxide powder previously impractical for HVOF systems. This paper describes the results of a programme of work carried out to study the effect of gas related parameters on the properties of Cr2O3, coatings deposited by HVOF using acetylene and acetylene based mixtures as fuel gases. It further describes the engineering of gas supply systems to overcome the working limitations of acetylene pressures and flowrates to achieve acceptable gas pressures and flow rates and subsequent particle temperature and velocity.
Effect of HVOF Gas Velocity and Fuel to Oxygen Ratio on the Wear Properties of Tungsten Carbide Coating
Authors: Korpiola K. , Vuoristo P. 
Published: May 2021

Abstract
The high quality of the thermally sprayed tungsten carbide coatings has been attributed to high particle velocity and relatively low particle temperature. Such thermal spray conditions can be obtained with the HVOF spray process. In comparison to the plasma spray process, in the HVOF spray process the high particle velocity and optimum particle temperature have been associated with very high gas velocity (&gt;1000 m/s) and a relatively low gas temperature (&lt; 2700 °C). In this work tungsten carbide coatings (WC-17Co) were sprayed by the HVOF process with a low and a high gas velocity of 1050 and 1560 m/s, respectively. The spray tests were carried out also with different hydrogen/oxygen ratios. The coatings were abrasion tested in order to find out how gas velocity and the fuel/oxygen ratio affect the coating quality and wear rate. Wear rates of the HVOF sprayed coatings were found to decrease with the higher combustion gas velocity. The coating quality and wear rate became also less sensitive to gas parameters with the increasing gas velocity. The coating microhardness and wear rate were also compared to hot isostatic pressed (HIP) reference material from the same spray powder lot. The HIP sintered test piece was found to be less wear resistant than the corresponding thermally sprayed coatings.
Effect of Processing Parameters on the Wear Resistance of Thermally Sprayed Epoxy Coatings
Authors: Bao Y. , Gawne D.T. 
Published: May 2021

Abstract
Plasma spray deposition of epoxies under normal conditions produces coatings with low wear resistance. The research shows that the difficulty in achieving satisfactory properties is a result of the rapid heat flow from the coating to the substrate, which suppresses the crosslinking reaction. The results indicate that the use of substrate preheating or ceramic undercoats enhances the wear resistance by promoting the curing reaction during spraying.
Experimental Approach to Adhesion between an Alumina Plasma-Sprayed Coating and Polymeric Substrate
Authors: Lucchese P. , Jeandin R. , Surdon G. , Delavernme A. 
Published: May 2021

Abstract
Thermal spray coating of fiber reinforced polymer (FRP) components has a high development potential to improve their wear, erosion and corrosion resistance. This paper deals with the optimization of plasma spraying conditions of alumina onto a FRP substrate, including the study of surface preparation. The so-called "Atmosphere and Temperature Controlled Process (ATC, patented by CEA)" was used to maintain the substrate temperature at a rather low level, i.e. near room temperature. Various surface preparation processes such as grit blasting, cleaning using the plasma torch and pre-coating with an intermediate bond coat were tested. The latter was shown to improve adhesion between the coating and the substrate significantly, when using 2 types of bond coats. One consisted of an additionnal fiber layer directly stuck to the substrate, the other of an intermediate thermally-sprayed PEEK layer. Results of adhesion tests were discussed in the light of interface characterization. Using a PEEK bond coat led to an adhesion strength between alumina and the substrate 3 times better than that for the material without any bond coat.
The Manufacture of SiC Fiber Reinforced ΑI2O3 Coatings by Plasma Spraying
Authors: Steffens H.-D. , Brune M. , Müller E. , Dittrich R. 
Published: May 2021

Abstract
Oftentimes, the application of bulk ceramics and ceramic coatings is limited by their poor fracture toughness and low strength. The mechanical properties of ceramics can be significantly improved by the incorporation of fibres, whiskers or particles of high strength, like SiC. Due to the high oxygen content of commercially available SiC fibers in combination with the elevated process temperatures, the SiC decomposes during plasma spraying. Therefore commercial SiC fibres were coated for temporary oxidation protection with C, TiN or Al2O3. By different agglomeration techniques using an organic binder SiC/Al2O3 composite powders were produced. Powder mixtures consisting of coated fibres and pure alumina as well as agglomerated powders have been successfully sprayed to form deposits. Recent results of the manufacture of SiC fibre-reinforced ceramic composites by plasma spray technology are presented. The properties of the composite coatings are compared to plasma sprayed pure alumina.
Thermal Spraying of Silicon Nitride - Based Powders
Authors: Thiel S. , Heimann R.B. , Herrmann M. , Berger L.-M. , Nebelung M. , Zschunke M. , Wielage B. 
Published: May 2021

Abstract
Thermal spraying of silicon nitride has been considered impossible because the high temperatures involved lead inevitably to decomposition/oxidation of the material. To address these issues, improved silicon nitride-based powders were developed, two of which have been tested as reported in this paper. The powders were applied using low pressure plasma spraying (LPPS) and the resulting coatings characterized based on microhardness, adhesion, and cohesion strength. Phase transformations of the powders during spraying were also investigated and preliminary optimization strategies by statistical variation of plasma spray parameters were tested.
The 5S Thermal Spray Systems
Authors: Browning J.A. 
Published: May 2021

Abstract
The "Shock Stabilized Supersonic Spray System" is currently designed for operation at oxygen supply pressures of 250 psig or 500 psig. It sprays both powder and wire. Low heat losses result in flame-jet temperatures appreciably higher than for chamber type geometries. Increased spray rates and deposit efficiencies result. Simultaneous powder and wire spraying can lead to zero coating stress allowing unlimited thickness build-up. Post flame quenching during wire spraying reduces liquid droplet temperatures nearly eliminating "splashing", while keeping the substrate cool.
Characterization of Copper and Steel Coatings Made by the Cold Gas-Dynamic Spray Method
Authors: McCune R.C. , Donlon W.T. , Cartwright E.L. , Papyrin A.N. , Rybicki E.F. , Shadley J.R. 
Published: May 2021

Abstract
The Cold Gas-Dynamic Spray Method (CGSM) is a means of producing coatings or free-standing structures from powder feedstocks, on metallic, polymeric or ceramic substrates, through the use of high particle velocities obtained by the control of gas dynamics in converging-diverging nozzles. The method expands the existing temperature-velocity domain of thermal-spray technology by permitting formation of coatings at relatively low temperatures with spray patterns governed largely by the gas dynamics of the nozzle. The coatings are formed by the energetic impact of the feedstock particles, whereby inter-particle bonding appears to be governed by the deformation of the particles accompanied by creation of copious amounts of fresh surface area available for interparticle bonding. Because of the novelty of the process, very little basic information exists regarding the mechanical properties and microstructure of the coatings. This work reports the outcome of investigations aimed at more clearly understanding the mechanical properties and microstructural characteristics of prototypical CGSM coatings formed from commercial copper and steel powders. Techniques include optical, scanning and transmission electron microscopies, microhardness and residual stress measurements. Early results suggest the materials to have significantly different properties than coatings made by more traditional thermal spray or cladding processes.
Peculiarities of the Structure and Phase Composition of Hydroxy Apatite Coatings Sprayed by Laminar Plasma Jet and Treated by Electron Beam
Authors: Klimenov V.A. , Ivanov Yu. F. , Karlov A.V. , Trophimov V.V. , Bataeva L.B. 
Published: May 2021

Abstract
The covering of titanium implants by means gas-thermal spraying of hydroxyapatite powders is an actual scientific, technical and medical problem. Application of hydroxyapatite for these purposes is more preferable. However, the problem of its structural and cyclic strength under conditions of bioenvironment response determines of application areas of such coatings and reliability of them usage. Structure and phase composition of hydroxyapatite coating under plasma spraying on titanium substrates and their changing, caused as conditions of forming coating on its increasing, so and conditions of spraying an laminar and turbulent plasma streem were studied. Exact belief about the crystalline structure and phase composition of coating is obtained by methods electronic microscopy and X-ray analysis. Changing of coating structure after sintering in the vacuum and electron beam melting in the vacuum is discussed.
Thick Coatings(&gt;1.5 mm) of CoNiCrAlY Sprayed by HVOF
Authors: Mingotaud N. , Bertoli A. , Fauchais P. 
Published: May 2021

Abstract
Spherical CoNiCrAlY powders (~45 + 5 μm) were sprayed using a Jet Kote II HVOF gun working with propane and oxygen. The coatings sprayed on two base materials: Inconel 625 (Ni base) and MarM 509 (Co base) were between 1,6 and 3 mm thick. The aim of the study was to examine the adherence problems in relation with this thickness and the imposed thermal cycles (thermal diffusion treatment and aluminizing). The studied parameters were the expansion coefficients evolution before and after the different treatments and the residual stresses between coating and substrate measured by incremental hole dilling method.
Microfinishing Behavior of Chrome Oxide Coatings on Anilox Print Rolls: High Power vs. Conventional Plasma Spray
Authors: Sampson E. , Miller R. , Lacourse S. 
Published: May 2021

Abstract
Anilox rolls require dense, adherent chromium oxide coatings capable of the highest quality microfinishing and laser engraving. Process economy and high deposition rate are also essential. Increasingly, anilox roll job shops are spraying such coatings using a high power plasma system, prompting this detailed investigation of processes, powders, and finishing. This paper evaluates how the material and the process influence the finished texture and engraving quality. Criteria for a successful coating are defined. The effects of plasma process, powder type, and coating microstructure on finish and engraveability mc analyzed in detail and practical recommendations are made. The test matrix includes high power and conventional plasma spray systems, three commercial chromium oxide powders used in anilox roll spraying, and three commonly used finishing methods.
Gas Dynamical Parameters of Detonation Powder Spraying
Authors: Kadyrov E. 
Published: May 2021

Abstract
Investigation of gas dynamics of detonation coating process is conducted. One dimensional model which allows calculation of particle exit parameters based on Chapman-Jouquet picture of detonation wave is developed. Kinetics of particle acceleration by a detonation wave show several novel features such as nonmonotonic dependence of velocity upon coordinate and inverse acceleration. Obtained results indicate that final particle velocity can be manipulated in a broad range by changing the gas mixture composition and the powder loading distance into the barrel.
Numerical Simulation of a Multi-Component Reacting Flow in a Supersonic DC Torch Nozzle
Authors: George C. , Pfender E. , Steffens H.-D. 
Published: May 2021

Abstract
Maximizing dissociated species transport in plasma assisted chemical vapor deposition (CVD), is important in many low pressure plasma jet processes. To deposit high quality diamond by low pressure plasma assisted CVD, it is important to maximize the atomic hydrogen transport to the substrate. One route to process improvement is to explore ways in which unstable species transport can be maximized. A two-dimensional computational model of a supersonic contoured nozzle attached to a dc torch will be described for examining the chemical non-equilibrium of the flow. If the fluid dynamic time scales of interest are faster than the kinetic time scales of interest, it is believed that unstable precursor transport can be controlled, improved and optimized. This paper will examine an implicit formulation for the numerical simulation of a multi-component reacting Ar-H2 plasma. It is found that dissociation, ionization and charge exchange reactions must all be included in a reaction model. The ionic species significantly alter the temperature profiles upstream of nozzle choking. However, to increase the number of hydrogen atoms at the nozzle exit, the arc attachment should be positioned as close as possible to the converging-diverging nozzle throat.