bluuebunny/crossref_metadata_2025 huggingface dataset:
Abundance and Diversity of Soil Arthropods in Different Habitats in Chitwan Nepal
Authors: Paudel A , Tiwari S
Published: August 2022

Arthropod diversity is generally influenced by the type of habitat in an agro-ecosystem. Crop diversity, soil types, nature of habitats (intensive, semi-intensive and natural), proximity to natural habitats, landscape complexity etc. are the major arthropod diversity influencing factors. Hence, this study was designed to investigate the diversity of various arthropod species among different habitats such as mango orchard, litchi orchard, vegetable field, organic field and uncultivated land during March 2021. Arthropod sampling was taken on every three- day interval using pitfall trap. The composition, relative abundance, and diversity indices of the arthropods of five different habitats were analyzed. Maximum abundance was recorded in uncultivated land (N = 398) and minimum in the vegetable field (N = 61). Shannon-Weiner Diversity Index (1.76) and species richness (9.67) were found highest in mango orchards. The greatest evenness was recorded in the vegetable field (0.91) and more dominance index was recorded in uncultivated land (0.60). There was a significant difference in total abundances of arthropods between vegetable fields than in the organic and uncultivated fields, being highest in uncultivated land followed by litchi, mango and organic field. Hymenopterans were the most abundant order (53.55%) followed by Coleoptera and Arachnida. These arthropods were crop pests and beneficial. Beneficial arthropods population was more than crop pests. Such beneficial arthropods play a vital role to deliver an ecosystem service. This study can help to develop a conservation and management protocol for beneficial arthropods in the agro-ecosystem.
नेपाली नाटकको युगीन प्रवृत्ति {Epochal Characteristic Features of Nepali Drama}
Authors: थापा Thapa अशोक Ashok
Published: August 2022

नेपाली नाटकको इतिहास झन्डै सवा दुई शताब्दी लामो छ । यसको आरम्भ अनुवाद रूपान्तरणसँग सम्बद्ध छ । हालसम्म प्राप्त तथ्यलाई मूल्याङ्कन गर्दा शक्तिवल्लभ अर्यालको हास्यकदम्ब (वि.सं. १८५५ तिर) लाई नेपाली नाटकको पहिलो खुड्किलो मानिन्छ । यद्यपि लिच्छविकाल र मल्ल कालमा सिर्जित नाटकका केही पाण्डुलिपिहरूको शोधन हुन बाँकी छ । प्रस्तुत लेखमा नेपाली नाटकको पृष्ठभूमिदेखि अहिलेसम्मको नाट्येतिहासको स्रस्टासापेक्ष अनुरेखाङ्कन  गरिएको छ । नेपाली नाटकका विषयमा अतीतमा भए गरेका पूर्वसामग्रीहरूको अवलोकन गरी निष्कर्षमा पुगिएकाले यस लेख द्वितीयक स्रोतको तथ्यमा आधारित छ । इतिहासमा अभिलेखन भएका दस्तावेजको तुलनात्मक पठन गरी निष्कर्षण गरिएकाले यस लेखमा तुलनात्मक विधिको प्रयोग भएको छ । प्रस्तुत लेखमा प्राप्त तथ्यहरू प्रस्तुत गर्न वर्णनात्मक विधिको प्रयोग भएको छ । यो लेख नेपाली नाटकको इतिहासको अनुरेखाङ्कनमा केन्द्रित छ । नेपाली नाटकको ऐतिहासिक पक्षलाई सङ्क्षेपमा निष्कर्षण गर्नु यस लेखको प्राप्ति हो । नेपाली नाटकसाहित्य उन्नत बन्दै गएको छ । नवीन चिन्तन र अन्तर्विषयकतालाई अबलम्बन गर्नु नेपाली नाटकको उल्लेखनीय उपलब्धि हो भन्ने यस लेखको निचोड रहेको छ । यसले आगामी दिनमा हुने शोधका लागि थप मार्गप्रशस्त गरेको छ ।
{Nepali drama has a history of about two and a half centuries. Translation and transformation were the first steps in the history of Nepali drama. According to the information received so far, Hasyakadamba is considered to be the first play written in Nepali. The play was thought to have been published in about 1855 BS. Nevertheless, some manuscripts of plays written during the Lichchhavi and Malla period remain unexplored. This article provides an overview of Nepalese drama's history from its beginning to the present. Previous research has served as a prelude. As a result, the source used here comes from Secondary sources. The comparative method has been applied in this article because it was obtained by comparing historical documents. This article presents information in a descriptive form. The writer tries to trace the history of Nepalese drama in this article. This article summarizes the historical aspect of Nepali drama. In recent times, Nepali drama has become more sophisticated. The article stresses as to how Nepali drama has achieved great success by adopting innovative and interdisciplinary thinking. Further research could be conducted on this topic in the future.}
दर्शन र साहित्य {Philosophy and Literature}
Authors: गड्तौला Gadtaula नारायण  Narayan
Published: August 2022

दर्शन र साहित्य ज्ञानका भिन्न शाखा हुन् । दर्शन ज्ञानप्रधान बौद्धिक वाङ्मय रूप हो भने साहित्य आह्लाद प्रधानरागात्मक वाङ्मय कला हो । तत्वमीमांसा र ज्ञानमीमांसाको विमर्शमा केन्द्रित दर्शनविधा तर्क एवं कार्यकरणको वस्तुनिष्ठ भाषामा व्यक्त हुन्छ भने साहित्य जीवन जगत्कै सत्यतथ्यलाई कल्पनाको जलपले रङाएर आलङ्कारिक, विरोधाभाषी,  लक्षणाव्यञ्जनामूलक भाषामा व्यक्त हुन्छ । यी दुई वाङ्मयका भिन्न विधा भए पनि दर्शन साहित्यबाट अभिव्यक्ति कलाको अपेक्षा गर्दै थोरै कलाको सम्पुटनबाट सम्प्रेष्यताको आलोक प्राप्त गर्दछ भने साहित्य दर्शनको वैचारिकतालाई अन्तःगर्भमा लुकाएर किञ्चित् बौद्धिक तुष्टि प्रदान गर्दछ ।
{Philosophy and literature are two different branches of knowledge. Philosophy is acknowledge-oriented intellectual rhetoric form while literature is an ecstatic melodic rhetoric art. Philosophy centers on the discussion of metaphysics and epistemology, which is expressed in the objective language of logic and causality. Literature, however, is expressed in figurative, contradictory and allegorical language by painting the realities of the world of life with the plated of imagination. Although these two genres of rhetoric are different, philosophy receives the light of communicativeness from the collection of art, expecting art of expression from literature, while literature provides a little intellectual satisfaction by hiding the ideology of philosophy in the womb. In this kind of interrelationship, one can see the interdependent relationship between philosophy and literature. The main purpose of this article is to study that relationship. For that, the data has been collected through library work and analyzed in a descriptive and explanatory method. Analyzing the relationship between philosophy and literature in this article, it has been concluded that philosophy is a branch of knowledge-oriented, objective, intellectual, causal, factual rhetoric and literature is a branch of rhetoric based on sentimental, heartfelt, subjective, imaginary truth.}
मुकुन्द–इन्दिरा नाटकमा धार्मिक अभिव्यञ्जना {Religious expression in the play Mukunda-Indira}
Authors: गुरागाईँ Guragain राधिका Radhika
Published: August 2022

प्रस्तुत लेखमा सनातन धार्मिक मान्यताका आधारमा बालकृष्ण समद्वारा लिखित मुकुन्द–इन्दिरा नाटकको विवेचना गरिएको छ । कृति विश्लेषणका निम्ति श्रुति, स्मृति लगायत शास्त्रीय ग्रन्थहरूमा उल्लिखित धार्मिक चिन्तनबारे विभिन्न समालोचकद्वारा मीमांसा गरिएका पुस्तकहरू एवं ‘मुकुन्द–इन्दिरा’ नाटकको अध्ययन गरी सैद्धान्तिक अवधारणा तय गरिएको छ । उक्त अवधारणाका आधारमा ‘मुकुन्द–इन्दिरा’ नाटकको विश्लेषण गर्दा परोपकार, कर्तव्य, नैतिक आचरणपूर्ण जीवन, ईश्वरप्रतिको विश्वास, प्रायश्चित्त, प्रेम, भक्ति, पाठपूजा एवं उपासनाको समष्टि स्वरूप नै धर्म हो भन्ने समको धर्मसम्बन्धी दृष्टिकोणको निरूपण गरी नाटकका विभिन्न सन्दर्भसहित विवेचना गरिएको छ । अध्ययन गुणात्मक पद्धतिमा आधारित छ र सामग्रीको विश्लेषण व्याख्यात्मक र विवेचनात्मक विधिमा गरिएको छ । यस नाटकमा जीवनको आधार नै धर्म हो र धर्मको आधार प्रेम हो भन्ने मुख्य विचारलाई नायिका इन्दिराको चरित्रबाट व्यञ्जित गरिएको छ भन्ने यस लेखको निष्कर्ष हो ।

{

This article discusses Bal Krishna Sama's play Mukunda-Indira on the basis of traditional religious beliefs. In the say way, old shruti, smriti, and other traditional literature are used to analyze the work. Mukunda-Indira play analysis is based on religious ideas expressed in many ancient scriptures. The literature reviewed, as examined by many critics prior to this, is regarded the theoretical foundation of the study. Analyzing the Mukunda-Indira play based on these established notions, the study is based on the author Sam's belief that religion is a blend of altruism, duty, moral conduct, faith in God, penance, love, devotion, recitation, and worship. This study, in particular, is based on a qualitative method, and the text is studied using explanatory and critical methods. The major premise of this play is portrayed through the character of the heroine, Indira, who believes that religion is the foundation of life and that religion is the foundation of love. This is the actual conclusion of this article.}
Application of FEM for the Estimation of Thermomechanical Properties of Plasma Sprayed Composite Coatings
Authors: Bolot R. , Aussavy D. , Montavon G.
Published: August 2022

The presence of defects such as voids, inter-lamellar porosities or cracks, provides a decrease of the effective thermal conductivity of plasma sprayed coatings as well as a decrease of the corresponding mechanical properties such as the Young’s modulus. In general, effective properties of thermal spray coatings are thus strongly different from that of the bulk material and have thus to be quantified to validate their in service performances. A complementary approach allowing understanding the relationships between the microstructure of a coating and its macro-properties is the use of Finite Element Modeling. The case of composite coatings is still more complicated due to the presence of different materials. In the present study, thermo-mechanical properties of a plasma sprayed composite coating were estimated by numerical modeling based on FEM. The applied method uses directly cross-sectional micrographs without simplification using a one-cell per pixel approach. Characteristics such as the thermal conductivity, the Young’s modulus, the Poisson ratio and the dilatation coefficient were considered. The selected example was an AlSi/polyester coating used as abradable seal in the aerospace industry.
Cold Sprayed MCrAlY as a Bondcoat Candidate for TBC Application
Authors: Ma X. , Ruggiero P.
Published: August 2022

As an emerging technique, cold gas dynamic spray is one of the latest tools for dimensional repair and coating applications. Cold spray (CS) utilizes high velocity particles as feedstock rather than high temperature to produce a coating without over melting feedstock, and thereby achieves a free-oxide coating. One of today’s critical coating applications is thermal barrier coating (TBC) for high efficiency turbine engine components, assisting and enabling today’s super alloys for turbine components to operate at a higher firing temperature. Many studies reveal that the formation of thermally grown oxide (TGO) on MCrAlY bondcoat, and the surface morphology profile of the bondcoat play paramount roles in failure modes and lifetimes of TBCs. This work has been focused on exploring the feasibility of CS MCrAlY as a bondcoat candidate for TBC application by comparing with those deposited by thermal spray processes, mainly plasma spray (APS) and high velocity oxygen fuel (HVOF). In this work, the features and properties of CS coatings were characterized mainly on microstructure, surface morphology, and TGO formation in isothermal oxidation test at 1100°C. Also, CS bondcoat and its thermal barrier coating were tested together with APS and HVOF formed TBC coatings. CS NiCoCrAlY coatings are identified with some unique aspects and characteristics: A desirable microstructure can be achieved, with oxide-free and high density. Solid solution of NiAl phase at local regions of grain boundaries is discovered; CS-bondcoat has a honeycomb network-like surface morphology. Long-range roughness is characterized from all honeycomb networks, and short-range roughness from the peaks within individual network cells; Kinetic curve of isothermal oxidation test at 1100°C indicates that a low-rate and stable TGO scale is formed on CS-bondcoat; and thermal cycling test demonstrates that CS-bondcoat TBC and APS-TBC have higher resistance to the spallation of ceramic topcoat.
High Sintering-Resistant Plasma-Sprayed Thermal Barrier Coatings Designed with Large Two-Dimensional Inter-Lamellar Pores
Authors: Liu Tao , Zhang Shan-lin , Luo Xiao-tao , Yang Guan-Jun , Li Cheng-Xin , Li Chang-Jiu
Published: August 2022

Atmospheric plasma sprayed (APS) thermal barrier coatings (TBCs) with lamellar structure exhibit low thermal conductivity and low stiffness. However, high temperature exposure for certain long duration causes the sintering which heals two-dimensional (2D) inter-lamellar pores and intrasplat pores. Such sintering effect increases the stiffness and thermal conductivity of the coatings and consequently reduces the stability and durability of TBCs. It can be expected that large 2D pores with a wide opening is difficult to be eliminated. In this study, inter-lamellar 2D pores with large opening width were fabricated in the La2Zr2O7 (LZO) coatings through spraying LZO+SrO coatings and removing the SrO splats in the water. Then, the conventional LZO coating and the porous LZO coating were subjected to high temperature exposure in the air at 1300 °C for different durations. The microstructure evolution especially in terms of the shape and density of inter-lamellar 2D pores was examined. In addition, the change of thermo-physic properties and the mechanical properties of the coatings with increasing exposure duration were studied. Results show that the 2D pores in LZO coating created by those SrO splats inherit primarily large opening width from 200nm to about 1 µm which endows the LZO coating with high sustainability at high temperature environment. Under thermal exposure at 1300°C, it was found that 2D pores resulting from SrO splats are free from healing while conventional 2D inter-lamellar pores with small opening width formed during splat cooling became healed rapidly. Thus, thermal conductivity and Young's modulus of the conventional LZO coating increased rapidly, while unhealed 2D pores in the highly porous LZO coatings contributed to the low Young's modulus and low thermal conductivity of LZO coating with remarkably high stability. With addition of 30% SrO in spray powder, a LZO coating with a thermal conductivity of about 0.39 W.m-1.K-1 in the as-prepared state was obtained. The coating maintained a thermal conductivity of 0.57 W.m-1.K-1 even after 100 hours exposure at 1300°C. The present results indicated that high sintering-resistant thermal barrier coating can be fabricated though designing inter-lamellar 2D pores with large opening width in the coating by the present novel approach.
Improving the Corrosion Resistance of Thermal Barrier Coatings against CMAS by Depositing Top Ceramic Layer of Enhanced Splat Bonding
Authors: Liu Tao , Wang Li-Shuang , Yao Shu-Wei , Yang Guan-Jun , Li Cheng-Xin , Luo Xiao-Tao , Li Chang-Jiu
Published: August 2022

The corrosion resistance of thermal barrier coatings against CMAS deposit at high temperature is significantly affected by the microstructure of the coatings. Enhancing the bonding ratio between splats can reduce the inter-connected pores and then obstructs the penetration of the molten CMAS into the coatings. In this study, atmospheric plasma sprayed ZrO2 contains 8 wt. % Y2O3 (8YSZ) coating with improved lamellar bonding ratios was deposited with full-molten droplets at an enhanced deposition temperature. The microstructure of the dense 8YSZ coating and conventional 8YSZ coating before and after thermal exposure with CMAS were characterized. It was clearly revealed that by adjusting the microstructure and designing a ceramic layer with high bonding ratio, the corrosion resistance of the thermal barrier coating could be enhanced. Moreover, by designing double-ceramic-layer (DCL) TBCs composed of a porous ceramic layer and well-bonded ceramic layer, the TBCs with high CMAS corrosion resistance and low thermal conductivity can be achieved.
Influence of APS Process Parameters on Morphologies of YSZ-Polyester Abradable Coatings
Authors: Aussavy D. , Bolot R. , Montavon G. , Peyraut F. , Szyndelman G. , Gurt-Santanach J. , Selezneff S.
Published: August 2022

Abradable seals are used in aircraft engine compressor and turbine to decrease fuel consumption. Their role is to minimize the clearance between the rotating blades of an engine rotor and the casing to reduce air leakages (compressor) or air-fuel combustion product leakages (turbine). Operating temperatures in turbines (up to 1800°C) can induce a thermal expansion of the blades and give rise to contacts providing damages to the blades or casing. Thus, in case of contact, the blade should remove the abradable seals applied to the casing without being damaged. Besides, the seal must be resistant to the turbine environment. Direct relationships have been observed between plasma spray operating parameters and abradable coating performances. The aim of this study is to determine those relationships for YSZ-Polyester abradable composite coatings. This study is conducted within the frame work of the 7FP European project E-BREAK to reach the environmental objectives of the European Advisory Council for Aviation Research and innovation.
Investigation of the Deposition Mechanism of Cold Spray onto Carbon Fibre Reinforced Polymers
Authors: Che Hanqing , Yue Stephen , Vo Phuong
Published: August 2022

Carbon fibre reinforced polymers (CFRPs) are more and more used in a wide range of industries, especially in the aerospace industry, but their low electrical conductivity has limited their application. During the past few years, metallization of CFRP has attracted increasing interest. To make the polymer composites electrically conductive, a conductive media must be either embedded into or coated onto the composites. Cold spray is one coating approach to achieve this. In this work, metallic powders were cold sprayed onto the CFRPs used in aircraft by using two different cold spray systems. The coatings as well as the coating/substrate interfaces were characterized and the deposition mechanism onto the CFRP substrate was determined.
Thermal Gradient Behaviour of TBCs Subjected to a Laser Gradient Test Rig—Simulating an Air-to-Air Combat Flight
Authors: Lima Rogerio S. , Marple Basil R. , Marcoux Pierre
Published: August 2022

A computer-controlled laser test rig (using a CO2 laser) offers an interesting alternative to traditional flame-based thermal gradient rigs in evaluating thermal barrier coatings (TBCs). The temperature gradient between the top and back surfaces of a TBC system can be controlled based on the laser power and a forced air back-face cooling system, enabling the temperature history of complete aircraft missions to be simulated. An air plasma spray (APS) deposited TBC was tested and, based on experimental data available in the literature, the temperature gradients across the TBC system (ZrO2-Y2O3 YSZ top coat / CoNiCrAlY bond coat / Inconel 625 substrate) and their respective frequencies during air-to-air combat missions of fighter jets were replicated. The missions included (i) idle/taxi on the runway, (ii) take-off and climbing, (iii) cruise trajectory to rendezvous zone, (iv) air-to-air combat maneuvering, (v) cruise trajectory back to runway and (vi) idle/taxi after landing. The results show that the TBC thermal gradient experimental data in turbine engines can be replicated in the laser gradient rig, leading to an important tool to better engineer TBCs.
Transient High Heat Load Performance of Thick VPS W Coating on Relatively Large CuCrZr Substrate
Authors: Deng Chunming , Liu Min , Xu Liping , Zhou Kesong , Deng Changguang , Kuang Ziqi , Zhang Xiaofeng
Published: August 2022

Plasma Facing Materials (PFMs) suffer from very high heat load including quasi-stationary high heat load during normal operation and transient events with extremely high heat load during normal plasma operation and off-normal events. In this paper, W/Cu functional gradient coating was applied on CuCrZr substrate (250mm × 120mm × 30mm) with compositionally gradient W/Cu as bond coat (0.4-0.6 mm) and 1.5 mm thickness W coating as top coat via VPS for continuous deposition duration of 5 h. VPS-W/CuCrZr mockup with built-in cooling channel was prepared for evaluating the transient vertical displacement and plasma disruption events applied by high energy electron beam. The formation of cracks and surface melting of VPS W/Cu mockup were investigated under the two transient high heat loads (HHL). The coatings were able to absorb about 2 MJ/m2 in HHL without significant damage.
Effect of Blasting and Spraying Parameters on the Adhesion of Arc Wire Sprayed Aluminum Coatings
Authors: Paul S. , Aldhous P.J. , de Villiers Lovelock H.L.
Published: August 2022

The application of aluminum coatings onto steel for corrosion mitigation is governed by standards specifying surface cleanliness and roughness prior to coating, and minimum coating bond strength. Controlling the surface preparation and spray parameters to achieve the specified surface condition and coating bond strength is challenging, particularly for manual on-site work. In this research, the process parameters were varied and the effect on surface quality and coating adhesion determined. It was found that blasting at angles as low as 30° from the surface, and varying stand-off distances up to 100 mm from the optimum, produced an acceptable surface; whilst spray angles of 60° to 90° and stand-off distances up to 50 mm from the optimum produced acceptable coatings with adhesion above 20 MPa. Adhesion appeared unaffected by a limited amount of remaining mill scale, but was reduced to ≈15 MPa when the surface chloride content was increased from 2 to 20 μg cm-2.
Fast Coating Deposition Simulation for Path Planning and Iterative Net-Shape Optimization on Complex Workpieces
Authors: Wiederkehr T. , Müller H. , Hegels D. , Tillmann W. , Hagen L.
Published: August 2022

For coating increasingly complex geometries that require a high accuracy with respect to a near net-shape coating distribution, the use of computer-aided path planning algorithms is mandatory to minimize the need for expensive prototyping experiments. During the planning process, coating simulations are typically evaluated frequently, thus both fast and accurate simulations greatly enhance the potential to find optimal path solutions. In this contribution, an efficient approach for computing the coating thickness on complex workpieces is presented, which makes use of the computational capabilities of mainstream graphics hardware to achieve simulation times well within the single-digit range of seconds for average-sized workpieces. Using a semi-automatic, measurement-based calibration routine, this simulation can easily be adapted to different processes. The simulation has been coupled with a path-optimization approach and was successfully utilized to enhance the deposition accuracy in the context of applying wear-resistant coatings to deep-drawing tools by means of a TWAS process.
High Stability, High Enthalpy APS Process Based on Combined Wall and Gas Stabilizations of Plasma (Part 2: Plasma Properties and Process Operating Window)
Authors: Belashchenko Vladimir , Zagorski Alexander
Published: August 2022

A recently developed air plasma spray (APS) process and a torch based on the combined wall and gas stabilizations of plasma (C+Plasma) has demonstrated extremely wide operating window and capability to efficiently generate both argon and nitrogen based plasmas including high enthalpy N2- H2 ones. The present paper aims to describe new areas of the extended C+Plasma operating window, in which a significant increase in the APS sprayed coating quality and process efficiency should be expected. The paper includes a brief analysis of properties of different plasmas as well as specifics of coating formation. Analysis showed that with the high enthalpy N2-H2 plasmas a significantly higher heat transfer potential and higher flexibility in controlling the particle acceleration can be achieved than with the argon based plasmas. Consequently, C+Plasma can enable better treatment of sprayed particles, which results in better deposit efficiency and improved coating properties.
Improvement of Corrosion Resistance of Thermal-Sprayed Stainless Steel Coating by Addition of Some Deoxidizing Elements
Authors: Era H. , Hashimoto K. , Sakoda N. , Zeng Z. , Sako S.
Published: August 2022

A modified stainless steel coating, named as M-SUS here, was prepared by the air plasma spray process (APS) and the high velocity flame spray process (HVOF) and compared with a conventional stainless steel (JIS: SUS316L). Anodic polarization tests using NaCl, HCl solutions, neutral salt spray test, and exposure test in actual tank for HCl storage were employed for the evaluation of corrosion resistance. Structure of the coatings was investigated by use of optical microscope, scanning electron microscope, electron probe micro-analyzer, and transmission electron microscope. It was found that the coating M-SUS exhibited a remarkably superior corrosion resistance by all tests mentioned above, compared with the conventional ones. Although both of the coatings compose of gamma-austenite (γ-Fe) and delta-ferrite (δ-Fe) phases, the coating M-SUS reveals much less oxide with chromium and more delta-phase enriched with molybdenum. Another exposure test using a mixed acid of 25%HNO3 and 75%HCl yielded that the δ-Fe was not etched out but the γ-Fe vanished, that is, the δ-Fe of M-SUS has a strong anti-corrosion property. It is considered that the superior corrosion resistance of coating M-SUS is attributed to the extensive formation of anti-corrosive δ-Fe and inhibition of chromium depletion resulting from oxide formation.
Improving Cold Sprayability—Mixed Metal Powders
Authors: Yue Stephen , Wong Wilson , Aydin Huseyin , Mongrain Rosaire , Barua Rajib , Vo Phuong , Dolbec Richard
Published: August 2022

In this paper, it is shown that mixing metal powders can lead to improvements in cold sprayability (i.e. increases in the deposition efficiency and decreases in the porosity) of the ‘matrix’ powder. This finding is illustrated with the following ‘binary’ mixtures: Ti – 6Al-4 V and commercial purity Ti; stainless steel and iron; spherical tantalum with irregular tantalum and two types of spherical tantalum with different characteristics. It is shown that a critical addition can significantly influence cold sprayability, but above this, there is little change in cold sprayability. Hardness differences are considered to be the first order influence, but differences in particle sizes and morphology may also be contributing factors.
Improving the Fatigue Resistance of Warm Sprayed WC-CoCr Coatings by Micro-Finishing
Authors: Tillmann W. , Nebel J. , Schaak C. , Biermann D. , Goeke S. , Matthäus G.
Published: August 2022

Automotive, aerospace, and energy applications demand for reliable coating systems to enhance the operating efficiency and the lifetime of processes, machines, and components. HVOF sprayed WC-CoCr coatings are commonly used, especially for wear resistant applications. Due to their high hardness and adapted corrosion resistance WC-CoCr coatings show perfect preconditions for highly stressed tribological systems. However, dynamic loads, caused by vibrations, alternating temperatures or cycling are challenging issues. Fatigue cracking and delamination can occur, resulting in fatal damage of the coated component. Therefore, crack and fatigue resistant high performance coatings are needed. In this research work, the influence of the substrate pre- and post-treatment (grit-blasting and micro-finishing) on the fatigue behavior of warm sprayed WC-CoCr is investigated. It was determined that the fatigue behavior of the applied coating can be improved by micro-finishing. The smooth surface structure results in a low interface roughness. This significantly reduces notching effects under load and enhances the fatigue strength of the specimen.
Investigation of a Pulsed Current Wire Arc Spray Process
Authors: Kirner S. , Atzberger A. , Zimmermann S. , Schein J. , Forster G.
Published: August 2022

In order to improve the wire arc spray process an inverter power source (PS) from gas metal arc welding (GMAW) process was used to evaluate the influence of current modulation on the formation of coating particles. Using the inverter PS allowed the application of high current pulses with varying amplitude and frequency. It was shown that particle formation can be limited to the high current phases, and that a strong interaction with the gas flow can be observed. The investigations suggest that using this technology new parameters may be introduced to control the wire arc spray process.
Offline Acoustic Plasma Spray Nozzle Wear State and Characteristic Identification
Authors: Blair Taylor , Pickrell Gary , Batra Romesh , Cybulsky Michael , Sinatra Raymond
Published: August 2022

Wear of plasma spray nozzles is a documented source of variation in the plasma spray process. Current wear detection relies upon observed gun voltage drops during operation. Operating voltage or hours of operation are rarely recorded when nozzles are changed over resulting in the loss of nozzle wear state knowledge. An offline means of determining wear state of GH type nozzles for OM 9MB plasma spray guns has been developed. By recording and analyzing the acoustic signal of a controlled gas flow through each nozzle, 28 nozzles were accurately categorized by their degree of wear. This test also allowed for the distinction between three manufacturers of new GH nozzles. Degree of wear was determined using bore profilometry and verified by voltage drop. This method allows for improved quality assurance and enhanced useful nozzle life.
Output Signal Characteristics of Thyristor- and Transistor-Controlled Power Supplies and Their Influence on the Electric Discharge in a Plasma Spray Process
Authors: Koschnitzke Hartmut , Nabavi Majid , Jagow Uwe , Schwenk Alexander
Published: August 2022

In this study, two different types of power supply are used in order to analyze the influence of the current output characteristics on the electric discharge characteristics. Three different plasma spray guns, namely F4, 9MB and SinplexPro, are studied with the use of different powder feedstock materials (Metco 204C-NS, Metco 71VF-NS, Metco 450NS and Hydroxyapatite C) by measuring the real-time gun voltage and current as well as the frequency spectra of the electric discharge during the spray process. In addition, a metallurgical analysis of the spray coatings is done in order to investigate the influence of the electric discharge characteristics on the spray coating quality in terms of the average coating porosity, hardness, deposition efficiency, degree of oxidation and microstructure.
Robot Kinematic Analysis for Torch Setup Optimization in Thermal Spraying
Authors: Chen Chaoyue , Deng Sihao , Liao Hanlin , Montavon Ghislain
Published: August 2022

Nowadays, the application of industrial robots in the field of thermal spray becomes gradually important. A desired coating quality depends on the factors such as a balanced robot performance, a uniform scanning trajectory and stable parameters (e.g. scanning step, spray angle, relative speed). Meanwhile, all these factors will affect the coating formation and the mass and heat transfer. As a result, the kinematic optimization from all these aspects is the key factor for thermal spray applications. In this study, the robot performance will be optimized from the aspect of torch installation on the robot. Robot kinematic parameters will be obtained from off-line programming software and analyzed by statistics method. The results showed that this method can optimize the robot performance from the view of robotic kinematics. It can also assign the amount of motion reasonably to each axis of the robot during the process, to achieve the constant relative scanning speed.
The Influence of Residual Stress on Wear Resistance of Thermal Spray Coatings
Authors: Tillmann W. , Luo W. , Selvadurai U.
Published: August 2022

The wear resistance of thermal spray coatings mainly depends on coating properties such as the microstructure, hardness, and porosity, as well as on the residual stress in the coating. The residual stress is induced by a variety of influences e.g. temperature gradients, difference of the thermal expansion coefficient of the coating / substrate materials, and the geometry of the components. To investigate the residual stress, the Impulse Excitation Technique was employed to measure the Young’s and shear moduli. The residual stress was determined by using the hole-drilling method and X-ray diffraction. Pin-on-Disc and Pin-on-Tube tests were used to investigate the wear behavior. After the wear tests, the wear volume was measured by means of a 3D-profilometer. The results show that the value of the residual stress can be modified by varying the coating thickness and the substrate geometry. The compressive stress in the HVOF-sprayed WC-Co coatings has a significant positive influence on the wear resistance whereas the tensile stress has a negative effect.
Three-Zone Anode Geometry—The Disengagement of Classic Nozzle Design for Atmospheric Plasma Spraying
Authors: Mihm Sebastian , Thomas Georg , Kuhn Rolf
Published: August 2022

Characteristics of atmospheric plasma spraying based on single-cathode-anode-systems like the F4 gun with convergent-cylindrical nozzle designs, are voltage fluctuations caused by periodically changes of the arc length. As a result continuous varying plasma flow properties lead to inhomogeneities during energy transfer to injected powder particles and variations of coating quality and process efficiency. With an adjusted convergent-divergent nozzle design and optimized high energy plasma parameters it is proven that process efficiency and stability could be significantly increased, also due to the reduced arc movement. A drawback in this case is the increased anode wear which needs to be optimized to secure industrial usage. Aim of this work was to minimize the anode wear of contoured convergent-divergent nozzles by using high efficient plasma parameters. Therefore arc characteristics in different nozzle designs were analyzed and the influence of the geometry to arc anode attachment was investigated. Consequently a stepwise optimization of anode wear by keeping the plasma fluid dynamic properties almost constant could be achieved. The results contribute to understanding of the arc characteristics in atmospheric plasma spraying. Also a new concept of a ”three-zone anode geometry“, convergent-inlet-section, cone-shaped arc movement section and a divergent plasma fluid shape section was developed.
TixAlyN Coating Manufacturing by Reactive Very Low Pressure Plasma Spraying (R-VLPPS)
Authors: Vautherin B. , Planche M.-P. , Montavon G. , Quet A. , Bianchi L.
Published: August 2022

Very low pressure plasma spraying (VLPPS) is an emerging process allowing manufacturing oxide and metallic coatings by condensation of vapors generated by feedstock powder vaporization. This process operates at unusually low pressures, typically between 100 and 1000 Pa. This paper aims at presenting recent developments for manufacturing Ti,Al,N coatings via a reactive mode. At first, nitrogen was used as the primary plasma forming gas to enrich spraying surrounding with nitriding species. Plasma jet mass enthalpy and substrate surface temperature were varied to evidence nitride phase formation during spraying. Then, a secondary nitrogen injection was implemented and located close to the surface to be covered in view of creating a continuous nitrogen supply to promote the nitriding mechanisms on the surface. SEM, XRD, GDOES and NHT were implemented to characterize coatings structure. This study highlights the nitrides formation versus spray operating conditions. The microstructural and mechanical features as well as the chemical composition are presented.
Understanding the Formation of the Limited Inter-Lamellar Bonding in Thermal Spray Ceramic Coatings Based on the Intrinsic Bonding Temperature Concept
Authors: Yao Shu-Wei , Yang Guan-Jun , Li Cheng-Xin , Luo Xiao-Tao , Li Chang-Jiu
Published: August 2022

Thermally sprayed coatings exhibit a lamellar structure with a bonding ratio less than 32% when a coating is deposited at ambient temperature. The lamellar bonding is one of the most important factors controlling the mechanical, thermal and electrical properties of the coatings. However, it is not clear why only limited lamellar bonding exists in a thermal spray coating even though many studies have been focused on the formation of bonding. In our previous study, it was found that there exists a critical deposition temperature for depositing ceramic splats to form the bonding with the underlying identical substrate, i.e., critical bonding temperature. Moreover, the critical bonding temperature is related to the interface temperature prior splat solidification which is determined by the glass transition temperature of splat material. In the present study, the critical bonding temperature and its relationship with interface temperature are used to understand the limited lamellar bonding ratio in a coating. A numerical simulation model involving heat transfer among depositing splat was proposed to establish the sufficient condition for liquid splat to form the bonding with the underlaying splats. The non-uniform splat thickness model was established to calculate theoretically the interface bonding formation. The calculation based on the model yielded a bonding ratio of 38.5% which agrees reasonably with the observed maximum interface bonding ratio.
Advanced 3-D Surface Finish System for Quantifying Thermally Applied Cylinder Bore Surfaces Including the Effect of Surface Porosity
Authors: McCormick Harold E. , Pisoni William J. , Crain John M.
Published: August 2022

This paper describes an advanced three-dimensional surface finishing system for quantifying the surface finish of thermally applied cylinder bore coatings. The system can measure surface finish values over the total area of use with and without including the effect of porosity, as well as size distribution and percent area occupied by surface porosity. It can also quantify torn and folded material developed during the honing or grinding process, as well as hone angles in cylinder bores. The system provides a powerful tool for cylinder bore finish development and monitoring the effect of porosity on the finish of plasma coated cylinder surfaces. The paper also discusses the development of replicate material and the comparison of finish values developed through direct imaging and replication. Additionally, it explores the quantification of torn and folded material and crosshatch angles in the cylinder bore finish. Overall, the system improves the quality of finishing data and provides a time-saving solution for production or research and development environments.
Anti-Adhesive, High Wear Resistant Coatings for the Paper Industry
Authors: Jungklaus H. , Etschmaier A.
Published: August 2022

Raising demands in industry lead to the request of better and enhanced functional surfaces, also on rolls parts in paper producing machines. Due to the higher usage of post-consumer recycled fibers on paper machines the run ability and machine cleanliness become a major issue. On one hand the contaminates called stickies can be responsible for sheet brakes, holes in the paper, web picking etc. On the other hand more sand containing waste paper enhances the impact on roll surfaces in operation. In this paper the different stickies (micro / macro / primary / secondary) and their impact on the paper production will be explained and the development to avoid stickies and contaminations together with high wear resistant coatings on roll surfaces in the paper machinery will be shown. Therefore a comparison of different materials and technologies regarding surface energy and peel force measurements are explained. Together with results of a pilot scale blade test rig the results in the market regarding anti stick properties wear resistance and corrosion resistance of the developed layer stack designs will be introduced.
Corrosion Testing of Thermally Sprayed Aluminum
Authors: Paul S. , Harvey M.D.F. , Ho Q.Y. , Yunus K. , Fisher A.C.
Published: August 2022

Corrosion rate determination is often based on linear polarization (LPR) technique, carried out on small specimens in a controlled environment. The current is measured when the specimen is polarized away from its corrosion potential and the corrosion current gives the corrosion rate using Faraday's law. An important parameter in this calculation is the specimen area exposed. When testing rough, porous specimens such as thermally sprayed aluminum (TSA), the geometrical surface area does not represent the real surface area and hence the corrosion rate is not the actual corrosion rate. To measure the actual corrosion rate aluminum was thermally sprayed onto glass and the surface was characterized using a confocal microscope. These specimens were exposed to seawater at 25, 50 and 100°C, and the linear polarization resistance was determined using a potentiostat at room temperature. This was converted to a corrosion rate based on geometric and the actual surface area.
Development of Processing Windows for HVOF Carbide-Based Coatings
Authors: Ang Andrew Siao Ming , Berndt Christopher C. , Wade Scott A. , Howse Hugo
Published: August 2022

This paper discusses the development of optimized processing windows for spraying high quality metal carbide-based coatings using advanced particle diagnostic technology. The cermet coatings are produced via the high velocity oxygen fuel spray process (HVOF) and are intended to be used in severe service applications such as marine hydraulics. To develop suitable coating process parameters, the traditional “trial and error” method is not technically robust, is costly and time consuming. Instead we investigated the use of real-time monitoring of parameters associated with the HVOF flame jets and particles using advanced in-flight particle diagnostics. Subsequently, coatings can be produced with knowledge concerning the molten particle size, temperature and velocity profile. The analytical results allow identification of optimized coating process windows, which translate to coatings of lower porosity and improved mechanical performance.
Influence of Substrate on Cold Sprayed Titanium Coatings
Authors: Villa Vidaller M. , Haußler F. , Assadi H. , Gärtner F. , Klassen T.
Published: August 2022

High quality coatings of titanium can be obtained by cold spraying using high process gas temperatures and pressures. However, the performance of cold sprayed coatings is determined not only by the respective material properties and the impact conditions, but also by the temperature and properties of the substrate—including the already deposited— material. In the present study, cold spray of spherical titanium grade II powders was performed on titanium grade II, copper, and stainless steel substrates, using two sets of parameters and three different substrate temperatures. Single impacts and respective particle adhesion were investigated using wipe tests followed by a modified cavitation test. Higher bond strengths were achieved for substrates that were held at higher temperatures during spraying. Moreover, the electrical conductivity of coating, taken as a measure of particle-particle bonding quality within the coating, improved and the porosity decreased for increased substrate temperatures. The findings are discussed in view of the thermal conditions, as well as the mechanical response of the uppermost layer of the substrate/deposit set.
Multi-Scale Structured Composite Coatings by Plasma Transferred Arc for Nuclear Applications
Authors: Werry A. , Chazelas C. , Denoirjean A. , Valette S. , Vardelle A. , Meillot E.
Published: August 2022

In nuclear plants, the replacement of hardfacing Stellite, a cobalt-base alloy, on parts of the piping system in connection with the reactor has been investigated since the late 60’s. Various Fe-base or Ni-base alloys, Co-free or with a low content of Co, have been developed but their mechanical properties are generally lower than that of Stellites. The 4th generation nuclear plants impose additional or more stringent requirements for hardfacing materials. Plasma transferred arc (PTA) coatings of cobalt-free nickel-base alloys with the addition of sub-micrometric or micrometric alumina particles are thought to be a potential solution for tribological applications in the primary system of sodium-cooled fast reactors. In this study, PTA coatings of nickel-base alloys reinforced with alumina particles were deposited on 316L stainless steel substrates. The examination of coatings revealed a refinement of the microstructure. Under the conditions of the study, the addition of alumina particles did not improve the micro-hardness of coatings but improve their resistance to abrasive wear.
Failure-Analysis Case History—Shorted Winding in Motor
Authors: Silvus Stan
Published: August 2022

A large dc motor in a servo positioning system began behaving erratically whenever the rotor was in certain positions. This article describes the examinations and tests that were conducted to determine the root cause of failure, which turned out to be a shorted motor winding stemming form damage most likely caused by the tool used to pack the conductors into the core slot.
Localization and Analysis of Metal-Coating-Related Electromigration Degradation in the 65 nm Technology Node
Authors: Langer Eckhard , Andreas Meyer Moritz , Limbecker Pascal , Utess Dirk , Preusse Axel , Aubel Oliver , Thierbach Steffi
Published: August 2022

With the introduction of 65 nm technology, the cross-sectional dimensions of copper interconnect in some layers are now smaller than 100 nm, which translates to current densities on the order of several MA/cm2. Electromigration as a root cause for chip failure is thus a major concern and is still being examined. In this article, the authors present recent failure analysis studies on metal-coated copper interconnects, using OBIRCH techniques in combination with FIB cross-sectioning and SEM and TEM imaging.
Advanced Defect Characterization by STEM Analysis
Authors: Subramanian Sam , Rai Raghaw , Ly Khiem , Chrastecky Tony , Mulder Randy , Harber Keith
Published: August 2022

Localizing defects in one-of-a-kind failures can take days, weeks, or even months, after which a detailed physical analysis is conducted to determine the root cause. TEM and STEM play complimentary roles in this process; TEM because of its superior spatial resolution and STEM because it produces images that are easier to interpret and is less susceptible to chromatic aberrations that can occur in thicker samples. In the past, the use of STEM in FA has been limited due to the time required to switch between imaging modes, but with the emergence of TEM/STEM microscopes with computer controlled lenses, the use of STEM is increasing. This article provides an overview of STEM techniques and present examples showing how it is used to characterize subtle and complex defects in ICs.
Response to Counterfeit Integrated Circuit Components in the Supply Chain: Part II
Authors: Shade Gary F.
Published: August 2022

This is the concluding portion of a two-part article on counterfeit ICs. The first part, published in the November 2008 issue of EDFA, discussed the rise of counterfeit ICs and some of the techniques used to identify them. Part II describes a process for device authentication, from material procurement to laboratory analysis, and provides examples of its use. It also discusses ongoing efforts to remove counterfeit ICs from the supply chain.
Backside Infrared Imaging of Integrated Circuits Using Refraction-Assisted Illumination
Authors: LaLumondiere Stephen , Yeoh Terence
Published: August 2022

This article demonstrates a simple and robust backside illumination method for infrared imaging of ICs. The technique uses oblique illumination, which removes surface noise components while providing bright-field illumination under the surface, and requires only modest if any polishing of the backside of the substrate. As the examples in the article show, it can be implemented with a standard microscope with IR optics, yielding high contrast, high resolution images without the need for complex lenses, AR coatings, or sophisticated scanning electronics.