bluuebunny/crossref_metadata_2025 huggingface dataset:
Ligational aspects of some 4f metal complexes of a mesogenic Schiffbase, N,N’- di-(4-dodecyloxysalicylidene)-1’,3’-diaminopropane: Synthesis and spectral studies
Authors: Shrestha Prem , Shakya Pawan
Published: August 2022

A liquid crystalline (smectic-F and smectic-A phases)Schiff base, N,N′-di-(4-dodecyloxysalicylidene)-1′,3′-diaminopropane(abbreviated as H2L) and a series of lanthanide (III) complexes of the type [Ln2(LH2)3(NO3)4](NO3)2, (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho) have been synthesized and characterized by elemental analysis, mass spectrometry, FTIR, and UV-Vis spectral techniques. The IR spectral data imply bidentate chelation of the Schiff base in its zwitterionic form (as LH2) to the LnIII ions through two phenolate oxygens, rendering the overall geometry of the complexes possibly to distorted mono-capped octahedra. The optical and thermal behavior studies (POM & DSC techniques) reveal that despite H2L being mesogenic, none of the LnIII complexes synthesized under this study exhibits mesomorphism. Fluorescence studies show emissions of H2L and SmIII complexx.
Influence of Magnesium Oxide Nanoparticles on the Compressive Strength of Urea Formaldehyde Resin
Authors: KC Susma , Rai Nelson , Shah Sambridhi , Joshi Rajendra , Raut Naresh , Pradhanang Situ Shrestha , Pandit Rajesh
Published: August 2022

Urea Formaldehyde (UF) resins have good chemical resistivity and high thermal stability, making them an excellent choice in the construction industry. They, however, pulverize quickly and have low strength and toughness. In this work, magnesium oxide (MgO) nanoparticles were added to UF as nanofillers to influence its compressive strength. MgO nanoparticles were synthesized by reducing magnesium nitrate at different concentrations, using orange peel extract. X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) techniques were used to confirm the formation of MgO nanoparticles. XRD results showed the formation of 43 nm, 35.28 nm, and 32.5 nm sized nanoparticles for 0.1 M, 0.2 M, and 0.4 M concentrations respectively. The varying-sized MgO nanoparticles were used for the preparation of UF/MgOnanocomposite at different weight-percentage (wt-%) ratios. A comparative study on the compressive strength of Urea Formaldehyde resins and UF/MgO was performed. From the results, it was found that the addition of MgO nanoparticles to UF resin enhances the compressive strength at certain wt-% ratios.
Biological and Chemical Studies of Essential Oil and Extracts of Rhizome of Acorus calamus Linn
Authors: Timilsina Rajesh , Tandukar Pooja , Pathak Ishwor
Published: August 2022

The essential oil (EO) of the rhizome of Acorus calamus Linn. was isolated by using a Clevenger apparatus and extracts were prepared by cold percolation technique using the solvents hexane and methane. The chemical constituents of EO were analyzed by Gas Chromatography-Mass Spectroscopy (GC-MS) analysis. A total number of nine chemical compounds were identified and quantified occupying 100% of the total oil composition. The major chemical constituent was reported to be β-asarone (84.87%). Acid value, saponification value, and iodine number of the oil were measured and found to be 0.24 mg KOH/g, 0.42 mg KOH/g, and 31.75 g I2/100gm,  respectively. The antibacterial activity of the hexane and methanol extract was examined against two bacteria by the agar well diffusion method. The hexane extract showed antibacterial activity against E. coli with a zone of inhibition(ZOI)of 10 mm, and. subtilis with ZOI of 7 mm. The methanol extract showed antibacterial activity against B. subtilis only, with a ZOI of 4 mm. Hexane and methanol extract also showed significant antifungal activity against fungi C. albicans with a ZOI of 6 mm and 5 mm, respectively.DPPH assay showed that the percentage of free radical scavenging activity increased with an increase in the concentration of the extract. The total phenolic content of the methanol extract of A. calamus was found to be 48.36 mg/g GAE.
’मुनामदन’ खण्डकाव्यको स्वच्छन्दतावादी अवलोकन {A Romantic View of the Khandakavya 'Munamadan'}
Authors: घिमिरे Ghimire अम्बिका Ambika
Published: August 2022

वि.सं. १९९१ मा ‘पूर्णिमाको जलधी’ र ‘गरीव’ कवितामार्फत् नेपाली कविताका क्षोत्रमा स्वच्छन्दतावादी धारा भिœयाएका लक्ष्मीप्रसाद देवकोटाका सम्पूर्ण काव्य कृतिहरूमा स्वच्छन्दतावादी धारा नै मूल रूपमा प्रकट भएको पाइन्छ र उनको ‘मुनामदन’ खण्डकाव्यमा स्वच्छन्दतावादी चेतना प्रबल रूपमा प्रकट भएको देखिन्छ र उनले यस खण्डकाव्यमा स्वच्छन्दतावादी मान्यताअनुरूप प्रकृतिको आत्मपरक, प्रकृतिको वस्तुपरक, प्रकृतिको मानवीकरण, प्रकृतिको सुन्दर असुन्दर रूप, घटनाको पूर्व सङ्केतका रूपमा देखिने प्रकृति र आलम्बन अनि उद्दीपन विभावका रूपमा प्रकृतिको चित्रण गर्दै मुनामदन खण्डकाव्यमा आदर्शवादी मानवतावादी विचार, आध्यात्मिक जीवन दर्शन, स्वप्नाप्रतिको विश्वास, लोक तŒवप्रतिको आकर्षण, आत्मिक प्रेमको समर्थन, कारुणिकता, कल्पनाको उच्च उडान र सौन्दर्यमयी भावना जस्ता स्वच्छन्दतावादी चेतना प्रकट भएको छ भन्ने कुराको सूचना यस लेखमा दिइएकोछ ।
गद्यकवितामा लयविधान {Rhythm in Prose Poetry}
Authors: कार्की Karki सन्तोष Santosh
Published: August 2022

कवितालाई अन्य विधाबाट छुट्याउने आधार लय हो । यो कविताको आधारभूत तत्व पनि हो तर लय बिना कविता नै हुँदैन भन्ने चाँहि हुँदैन । पद्यकविता सामान्यत श्रुतिमधुरता र गेयात्मक हुने भएकाले यो लयात्मक हुन्छ । गद्यकवितामा ध्वनि, शब्द, पदावली, उपवाक्य, वाक्यहरूको पुनरावृत्ति, वाक्य ढाँचा, पङ्क्ति विन्यास, समानान्तरता वा आवृत्ति, विचलन, शब्दहरूको वैपरित्व, लेख्य चिह्नहरूको प्रयोग, अनुप्रास, सम्बोधक शब्दहरूको प्रयोग, विशिष्ट ध्वन्यात्मक शब्द, बिम्ब प्रतीक र अलङ्कार आदिले लय सिर्जना गर्दछ । गद्यकवितामा मुक्त लयको प्रयोग गरिन्छ । यसमा पनि लयात्मक, प्रवाहात्मक, सङ्गीतात्मकताजस्ता गुण रहेको हुन्छ । मुक्त लयमा पद्यमा जस्तो सोभैm लय देखिदैन तर त्यसको अन्तरवस्तु केलाउने हो भने एक प्रकारको मुक्त लय रहेको हुन्छ । पङ्क्ति विन्यासमा शब्ददेखि वाक्यसम्मका भाषिक एकाइहरू (न्यूनतमदेखि अधिकतम शब्दहरूको विवरण) असमान, अनियमित र विविध रूपमा आएका हुन्छन् । यस्ता पङ्क्तिहरूले कवितामा यति, गति र लयलाई विशिष्ट तुल्याउँछन् । जति बढी भाषिक एकाइहरूको पुनरावृत्ति हुन्छ, त्यति नै यति, गति र लयको स्थान उच्च बन्न जान्छ । त्यसैलै आवृत्ति हुँदा एक प्रकारको मुक्त लयको सिर्जना हुन्छ । गद्यकवितामा सीमित अनुपासको प्रयोग पाइन्छ । यसमा आद्यानुप्रास, मध्यानुप्रास र अन्त्यानुप्रासको प्रयोगले लय सिर्जना हुन्छ । पङ्क्तिहरूको सुरूमा, पङ्क्तिको बिचमा र पङ्क्तिको अन्त्यमा हुने अनुप्रास नै क्रमशः आद्यानुप्रास, मध्यानुप्रास र अन्त्यानुप्रास हो । यसैबाट गद्यकवितामा लयको निर्माण हुन्छ । गद्यकवितामा विभिन्न किसिमका लेख्यचिह्नहरूको प्रयोग गरिन्छ । यसले कविताको गति, यति, भाव र लयलाई व्यवस्थित बनाउँछ ।
वैदिक संस्कृतमा भाषिक चिन्तन {Linguistic Thought in Vedic Sanskrit}
Authors: खतिवडा Khatiwada सुस्मिता Susmita
Published: August 2022

भाषा मानवीय सम्प्रेषणको सशक्त माध्यम हो । भाषाको इतिहास मानव सभ्यताको विकास कालदेखि नै देखापर्छ । संस्कृत भाषा विश्वकै सबभन्दा पुरानो भाषा हो । भाषिक चिन्तनको सुरूवात भने घेरै पछि मात्र भएको पाइन्छ । प्रस्तुत अध्ययन भषिक चिन्तनको सुरूवात, वैदिक र लौकिक संस्कृतमा भाषिक चिन्तनका विषयमा केन्द्रित छ । अतः वैदिक साहित्यमा भाषिक चिन्तनको खोजी गर्नु यस अध्ययनको उद्देश्य हो । पुस्तकालयीय अध्ययनबाट प्राथमिक र द्घितीयक स्रोतका सामग्री सङ्कलन गरी अध्ययन, विश्लेषण, तुलना र मूल्याङ्कनका साथ भाषिक चिन्तनको खोजी गरिएको छ । यस अध्ययनमा वैदिक सभ्यता, वेदमा भाषिक चिन्तन, ब्राह्मण, उपनिषद, निघण्टु, निरूक्त, शिक्षा प्रतिशाख्यहरूमा भाषा सम्बन्धी धारणा र व्याकरणिक पक्षको व्यापकताको चर्चा गरिएको छ । मानव समाजको अस्तित्वदेखि नै भाषाको प्रयोग भए तापनि संस्कृत भाषिक चिन्तन भने इ. पू १५०० तिर देखि विकसित हुदै आएको देखिन्छ । प्रस्तुत अध्ययन मूलतः वैदिक र लौकिक वाङ्मयमा भाषिक चिन्तन के कस्तो छ ? भन्ने प्राज्ञिक जिज्ञासामा केन्द्रित छ । गुणात्मक विधिमा आधारित यस अध्ययन वैदिक र लौकिक वाङ्मयका सबै मूल कृति प्राप्त नभए पनि तिनलाई आधार मानेर रचिएका सन्दर्भ ग्रन्थ, लेख, अध्ययन वाट तयार परिएको छ । यस अध्ययनलाई पुस्तकालयीय सामग्रीको अध्ययन तथा विश्लेषणबाट सम्पन्न गरिएको छ ।
Open and Distance Learning Mode in Nepal: Practice and Challenges
Authors: Ghimire Nani Babu
Published: August 2022

Open and distance learning (ODL) is accepted as an alternative mode of education which is defined as a new trend in instruction wherein the learner is geographically separate from the source can involve in learning process. This study presents a clear figure of the current practice and challenges of ODL for ensuring access to higher education in the context of Nepal. As qualitative study, narrative inquiry research design was exercised and four participants were selected purposively to extract their experiences, understanding and perception on ODL through semi structured interview. The interviews were transcribed and thematically analysed developing two global themes in relating to literature. The findings of the study suggested that the practice of open and distance learning mode in Nepal is not so developed and people are not satisfied with its provision. It is not adequately managed and also not in the access to the target groups because of highly prioritized formal education system. The lack of physical facilities, electricity supply, Information Communication Technology (ICT) devises, unavailability of capable expert, lacking strong commitment of the concerned agencies to provide quality assurance are its challenges.
Awareness and Attitude towards Emergency Contraception
Authors: Khadka Roshani
Published: August 2022

Globally, unintended adolescent pregnancies pose a significant burden. One of the most important tools that can help prevent unintended pregnancy is the timely use of emergency contraception (EC), which in turn will decrease the need for abortions and complications related to adolescent pregnancies. The objective of this study was to assess awareness and attitude towards emergency contraception among secondary level students. A descriptive cross sectional study was conducted in grade eleven and twelve students in Manmohan Memorial College in 2020 Jan-Feb purposively. Out of total population, 105 sample students were randomly selected. A self-administered semi-structured questionnaire was used to collect the data. Among 105 respondents, highest proportions (41%) of the respondents were aged 17 years. Majority (75.2%) of the respondents was aware that oral contraceptive pills can be used as EC method. Majority (65.7%) of the respondents replied I pill as EC available in Nepal. (65.7%) of the respondents stated that awareness program is needed to be promoted by government, (62.9%) of the respondents said that information about EC is needed to be provided by educational institutions, (42.9%) of the respondents disagreed that abortion is better than using EC. Based on the findings of the study it is concluded that higher secondary level students tends to have awareness and positive attitude towards EC.
Responsive pedagogy for multi-lingual classroom
Authors: Pokhrel Mohan Mani
Published: August 2022

In this paper I explore the concept of diversity in the classroom. Diversity means difference in terms of race, language, age, faith, culture, ethnicity, and in other aspects. Nepal is a multicultural and   multi lingual country. Where more than 123 languages are spoken. Such as Nepali, Maithili, Bhojpuri, Tharu, Newari, Abadhi etc National language is Nepali in Nepal. Social structure is also different from society to society. There are racially different people. The main are   Bramhin, Chhettri, Rai, Gurung,Tamang, Magar, Tharu, Newar and others who caste live here. There are mainly ten types of religious categories reported in the census 2011 A. D. The large number of people are followed by Hindu. Whereas Hinduism is followed by (81.3%), Buddhism (9%), Islam (4.4%) and so on. Nepal has been diversified in terms of ethnicity, religion, traditions and culture. People respect the national feeling of unity in diversity. Nepal is multi-cultural, multi-ethnic and multi-lingual society so there are diversity in the classroom. In this paper I explore the diversity in the classroom and students' achievement. In this paper I have introduced multicultural education, cultural responsive pedagogy and student achievement. The conclusion of this study is responsive pedagogy address and support to the student's achievement in diverse classroom.
Proza Pawła Sołtysa – w kręgu poetyki
Authors: Grzelązka Izabela
Published: August 2022

The subject of this article is the prose of Paweł Sołtys, or more precisely, two volumes of short stories: Mikrotyki and Nieradość. Narration, space and autobiography are compared with the assumptions of small realism. There is also a reference to the context of contemporary prose, including its trend about Warsaw. The analysis of these categories aims to identify the poetics of Paweł Sołtys.
Nowoczesność i uniwersalność grekańskiej poezji Salvina Nucery
Authors: Janion Ewa Róża
Published: August 2022

This article discusses Salvino Nucera's (b. 1952) collection of poetry written in Greko (Calabrian Greek, Grecanic) – a language of a small community in Southern Calabria. The article focuses on the poetic strategies of constructing a modern subject in a language that is intrinsically connected to traditional pastoral culture and provides extremely limited vocabulary. It is argued that Nucera refers to the Calabrian landscape, often to specific places, typical elements of nature and everyday practices, which in his poetry become universal metaphors and create an image of a modern intellectual's complex identity.
Loved to Death
Authors: Varghese Ricky
Published: August 2022

Some viewers of Michael Haneke’s award-winning film Amour (2012) may read it “simply” as a film about assisted dying. Here, I explore how Haneke attended to the experiences of aging and disability, and how these categories inform intimate relations, in this case that of an aging middle-class heterosexual couple living in Paris. As the deterioration of the body intensifies, what does it mean for love itself to intensify to the point of surrendering to the demand of subjecting the one you love to death. Thinking alongside the work of Sigmund Freud and Kaja Silverman, I ask after what may happen if and when love has the capacity to demand upon one the annihilation of their beloved. How is the beloved remembered, preserved, and forgotten as they age, and what might it mean to see love as not merely a cure but also a thing that has the capacity to kill?
Determination of the effect of high intensity interval training on the physical structure of mature women
Authors: Musiyenko O. , Shutka H. , Artiukh V. , Sopila Yu. , Holubeva O. , Mazur T.
Published: August 2022

High-intensity interval training, or Tabata training, is a fitness training method that aims to perform the maximum number of movements in the minimum amount of time. We decided to establish the effect of high-intensity training according to the Tabata protocol on the physique of mature women. At the beginning of training, 2 rounds were conducted (August - September 2021), during November 2021 - January 2022, 3 rounds were conducted, in February 2022, 4 tabata rounds were already used, but, unfortunately, the study had to interrupt. The purpose of our work was to determine the effectiveness of high-intensity training according to the Tabata protocol on the physique of women of the second mature age. Standing height, weight, circumference of the body (chest, waist, shoulder, thigh, lower leg), thickness of fat folds, as well as derivative indicators: optimal mass, density, fat and fat-free components of the body were determined. In tabata training, we used plyometric exercises, strength exercises with own body weight, strength exercises with light weight. For example: jumps, push-ups, squats, lunges, jumps, sudden accelerations, fit ball exercises, punches and kicks, sprints, etc.

Objectives of the study: Determine the main anthropometric indicators of women of mature age of the control and experimental groups and calculate the derived indicators according to the appropriate formulas. To analyze the effectiveness of high-intensity interval training sessions (according to the Tabata protocol) on the indicators we determined.

As a result, it was established that high-intensity interval training sessions according to the Tabata protocol have a significant effect on the physical condition of the body of mature women. They have a significant impact on the anthropometric indicators of women of mature age. A significant decrease in the fat component of body weight, an increase in the muscle component, as well as a decrease in body weight and body contours (waist, chest, hip, and leg) were shown. In women who practiced according to this system, all the main indicators characterizing the physical condition quickly and significantly improved.
Organization of teaching of the discipline "physical culture and sports" in the conditions of distance education
Authors: Slukhenska R. , Litvinyuk N. , Bamburak V. , Toderash V. , Malanii V.
Published: August 2022

Forecasts regarding the specifics of the academic year 2022-2023 are different, because no one can predict military events and the behavior of the enemy even for the next few hours. In the conditions of the forced transfer of the educational process to a distance form of education, the question arose of resolving the contradictions between the traditional form (practical aspect) of physical education of students at the university and the need to organize this pedagogical process based on the use of distance educational technologies. Currently, we can say that at least a certain part of Ukrainian higher primary institutions will have a distance form of education, since a large percentage of institutions do not have properly organized and reliable shelter, some are destroyed, some are in the war zone, so a certain number, unfortunately, already in the occupied territories. The specifics of the distance learning organization of the subject "Physical Culture" in the conditions of forced distance learning or partially distance learning were discussed, the details of conducting practical classes in the Google meet system were characterized, and the features of the final control of the discipline were determined. For practical classes at the Bukovyna State Medical University, the basic types of motor activity are determined taking into account the material and technical base: fitness, sports games, general physical training. The elements of the developed model of implementation of educational programs of disciplines of the "Physical culture and sport" cycle were considered, taking into account the use of electronic learning and distance educational technologies.
Thermal Spraying-Application and Development Trends
Authors: Hangong W. , Liuying W.
Published: August 2022

With high speed development of modern industry, the research and application of thermal spray technology made more progresses, the thermal spraying technology was applied more and more widely in industry fields. At the same time, the people pay more and more attention to the development of thermal spraying industry. In the paper, the development trends of thermal spray were presented on the basis of analyzing the research and application of thermal spraying technology. Spray particle velocity is developed to high velocity. Thermal spraying equipments is developed to multi-functional and accuracy and save energy and high efficiency. Spraying materials is developed to nano structured material, preparation of Nano Structured Coatings is one of directions of development of thermal spray. Thermal Spray has more widespread application prospect in aerospace, environmental protection and biological implant fields.
Thermal Spray Based Rapid Manufacturing, Part Refurbishing and Reengineering
Authors: Mohanty P.S. , Hart A.
Published: August 2022

The ability to respond timely and cost effectively is bringing rapid manufacturing techniques into the mainstream production/repair arena. The Army can benefit from such technologies to avoid long lead times and high costs of procuring and inventorying replacement parts. But, a technology that offers versatility in terms of product size, cost and the ability to fabricate production components rapidly is yet to be available. This paper describes thermal spray technologies as applied to rapid manufacturing, part refurbishing and reengineering. A hybrid thermal spray system that can deposit a variety of materials with high throughput and density has been developed. Several generic materials that can meet the functional requirements of many parts and at the same time can be easily deposited by a thermal spray technique are discussed. An expert system software assisting the operator from CAD information, reverse engineering to part refurbishing is presented. Examples on the use of multiple schemes to remanufacture a part are also discussed. These schemes offer new avenues to fabricate replacement parts and/or salvage damaged parts and can benefit the Army considerably.
Reengineering of Boiler Feed Pump using High Performance Coatings
Authors: Chandak A. , Balasubramanian G.
Published: August 2022

Boiler feed pumps (informally termed as mini turbine owing to its criticality) in thermal power plants are prone to normal wear and tear over a period of time, which leads to loss of pump efficiency and sometimes accidental failures resulting in heavy damages and prolonged shut downs. Re-engineering approach using High Performance Coatings by Plasma & HVOF processes, has recently enabled to add new world-class dimensions by reclamation & complete overhauling of Boiler Feed Pump Internal Cartridges (6“ LL Pacific Pumps Inc USA and 200 KHI, BHEL, India make), in order to obtain increased life cycle, maintain pump efficiency, De-accelerated wear rate. This was accomplished by establishing perfect interrelationship of cartridge assembly, providing exacting tolerances to meet functional and assembly requirement, and incorporating international standards for protective wear shielding by Plasma & HVOF technology on wear prone critical components. This paper describes the Re-engineering methodology adopted to improve the performance of the Boiler Feed Pump with the help of surface modification using plasma and HVOF coatings on critical components showing wear patterns, which led to the development of proprietary ceramic and cermets coatings after extensive laboratory and field trials. The Reengineered Boiler Feed Pumps are showing superior performance at one of the major power generating unit in Central India.
Manufacturing of Metal Foam Composites Through Multifunctional Coatings – The New Easy Foam-Process
Authors: Liebscher C. , Maurer M. , Zhao L. , Lugscheider E.
Published: August 2022

Especially, composites of aluminium metal foams are of high potential for lightweight applications in automotive, aerospace and general engineering because of their excellent ratio of low weight and high stiffness. To fulfill the industrial need for these new materials as soon as possible, a new integrated manufacturing process concept has been developed and studied at our institute. The new “easyFoam-process” concept consists of four basic steps: production of semi-finished parts via the powder metallurgical route, forming of the foamable semi-finished part into a near net shape by extrusion or any standard aluminium-forming process, coating of the surface by thermal spraying and foaming by inductive heating. Thus it’s feasible to provide a fast, continuous and efficient production of metal foam composites with highly reproducible properties, resulting in eminent advantages over current techniques for foam sandwich production in terms of degree of anisotropy, statistical spread in foam properties and production economy. This process is also the only one being able to produce a graded pore structure in symmetrical parts of PM-aluminium foams. The thermally sprayed coatings serve simultaneously as mould and as future multifunctional coating. In this paper, some results of our first study in coating the foamable Al-tubes and inductive heating the coated parts are presented.
High Resolution Microstructural Investigations of Interfaces Between Light Weight Alloy Substrates and Cold Gas Sprayed Coatings
Authors: Wielage B. , Podlesak H. , Grund T. , Wank A.
Published: August 2022

Investigations on interfaces between light weight alloys (aluminum AA7022 and magnesium AZ91) and optimized cold gas sprayed (CGS) zinc-based coatings are carried out. The analyses include standard optical and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM). By using TEM resolution within nanometric dimensions is realized. Investigations by SEM show areas of an intensive mixing between substrate and coating material with a number of different grey values due to element contrast. By EDXS analyses in a 1 µm broad transition zone increased zinc concentration compared to the substrate material is detected. TEM investigations prove that in this transition zone no homogeneous solid solution exists, but additionally submicron and nanosized intermetallic phases with different concentration of aluminum, zinc and magnesium are found. Due to these results an intensive mechanical interaction must take place at the substrate-coating interface during CGS. Thus bond strength does not only depend on physical and chemical adhesion or thin metallurgically affected zones, but also highly on effects of mechanical alloying.
Production of Freeform Net Shape Components by Cold Gas Dynamic Spray
Authors: Morgan R. , Pattison James , Celotto S. , O'Neill B.
Published: August 2022

This paper reports on the development of a cold spray system to be used as freeform fabrication production route. Cold Spray is seen as a preferential method for additive manufacture as the cold nature of the bonding removes detrimental thermally induced stresses. The Cold Gas Dynamic Manufacturing facility is the first of its kind, housed in a CNC machining centre with integrated high-speed machining spindle for back machining of deposit material to tolerance. The process enables the production of complex geometries including undercuts through the use of a two material delivery system fed by separate powder feeders. By this method one material is used as a sacrificial support structure and removed through post-process techniques. The process is fully numerically controlled. The process is conducted inside a chamber, such that all process gas is recaptured for purification and recycling. The paper will report on the various aspects of component production and will also detail strategies and techniques for building complex component shapes. Abstract only; no full-text paper available.
Kinetic Deposition of Ti Coatings Using Gas Atomized Ti Powder Particles
Authors: Zhao Z. , Gillispie B. , Han T. , Patel N. , Eesley G. , Mantese J.
Published: August 2022

The kinetic spray process is a coating process that involves impingement of a substrate by metallic particles at high velocities. In this work, we investigated the kinetically sprayed Ti coatings, which were deposited onto different metallic substrates using gas-atomized powders. The powder particles were characterized in terms of size distribution, morphology, hardness, and explosibilty index. The propellant gas used for coating deposition was compressed nitrogen. The substrates were placed inside an enclosure filled with nitrogen gas during deposition. It was observed that Ti coatings can be deposited at relatively high deposition efficiencies using large particles (median size~ 100 mm). Ti coatings with a wide range of thickness and good macroscopic appearance were readily prepared. The particle temperature appears to have strong effects on the coating formation; deposition efficiencies of ~90% were achievable. Microscopic examination of the coatings revealed deposited Ti particles with significantly lower deformation when compared to ductile materials such as Al and Cu. As a result, the Ti coatings exhibited a high degree of porosity. Several methods were exploited in order to make the Ti coatings denser, including the incorporation of heavy, hard particles for in-situ peening during the coating deposition, and post deposition laser heating. Abstract only; no full-text paper available.
Nano- and Microcrystalline Cold Spray Coatings
Authors: Shmyreva T. , Knapp J. , Sedov V.
Published: August 2022

The Cold Spray coatings have been sprayed from binary eutectic alloy – Al-12%Si and from the complex composition iron-based alloy. The atomized Al-Si powder had close to microcrystalline (grain size around 1micron) structure, the Fe alloy powder had amorphous-nanocrystalline structure. Aluminum-based alloy was also sprayed with addition of up to 10% of aluminum oxide powder. The coating structure and properties have been investigated using optical microscopy, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, microcalorimetry, microhadness, tensile, bend, erosion and abrasion tests, and corrosion polarization tests. It has been shown that the Al-Si coatings have microcrystalline structure, and the Fe-based coating have amorphous-nanocrystalline structure similar but not identical to the feedstock powders. Cold Spray process has a specific mechanism to preserve the powders metastable structures. The coatings have enhanced hardness, wear and corrosion resistance. Abstract only; no full-text paper available.
Kinetically Sprayed Cu Coatings: Effects of Particle Characteristics
Authors: Zhao Z. , Gillispie B. , Han T. , Smith J.
Published: August 2022

The kinetic spray process is a coating process that involves impingement of a substrate by metallic particles at high particle velocities. During the last several years, significant advancements in the fundamental understanding of the process have been made at Delphi Research Labs, which allowed us to greatly to enhance our capability in spraying difficult-to-deposit materials, especially with relatively large particles as feedstock and compressed nitrogen as the propellant gas (a challenging combination). In this work, we investigated Cu coatings that were kinetically sprayed using large Cu particles (53-150 microns). The emphasis is placed on understanding the effect of powder particles on the coating formation by the kinetic spray process. The examined particle characteristics in the present study include particle size, shape and morphology, and microstructure. The results indicated that the coating formation by the kinetic spray process is controlled primarily by two fundamental variables of sprayed particles: particle velocity and particle temperature. Very large sized particles, in spite of their relatively low particle velocities (as a result of acceleration by nitrogen rather than helium), can be rendered to exhibit enhanced spray ability, comparable to smaller size particles. This can be achieved by properly controlling the particle temperatures. It is found that kinetic spray using large size Cu particles (~100 microns) can lead to dense Cu coatings, with 50-80% deposition efficiency. Abstract only; no full-text paper available.
Study of Magnetic Properties of Iron-Based Thermally Sprayed Coatings
Authors: Cherigui M. , Guessasma S. , Fenineche N.E. , Liao H. , Coddet C. , Craven J.
Published: August 2022

In this study, the magnetic properties of iron-based coatings obtained by HVOF thermal spraying were investigated. These properties were correlated to alloy type, heat treating temperature and coating thickness using artificial neural network method. Among coating characteristics, porosity is regarded as an influential parameter on the magnetic properties. Therefore, the role of the microstructure was particularly emphasized in this study. Magnetic properties, especially coercivity, showed a weak decrease with the addition of alloying elements. However, these properties remained nearly unchanged at high temperatures and for large coating thicknesses. Porosities are regarded as defects anchoring Bloch walls and consequently promoting an increase of coercivity.
Usefulness of 3-D Time Dependent Models and Steady 2-D Models in Plasma Spraying Engineering?
Authors: Mariaux G. , Vardelle A. , Fauchais P.
Published: August 2022

This paper presents a 2-D, steady and 3-D, time-dependent models of the atmospheric–pressure plasma spray process. The former focusses on plasma jet and particle behavior while the latter involves the modeling of plasma jet formation inside the nozzle and makes it possible to have some insight in anode erosion and coating geometry. Both models have been validated by comparing the predictions against experimental data. The input and expected output of both models will be discussed as their use in the engineering and operation of plasma spraying
Coatings Obtained by Low Pressure Plasma Spraying
Authors: Sokolov D.E. , Chwa S.-O. , Klein D. , Coddet C. , Nardin P.
Published: August 2022

Thermal sprayed protective coatings have gained widespread acceptance for a variety of industrials applications. This technology can be split into air plasma spraying (APS) and vacuum plasma spraying (VPS) according to the atmosphere during the deposition process. A number of advantages of VPS process such as avoiding oxidation or contamination of projectile, substrate and deposed coating; reducing the interaction between the plasma jet and the environment are obvious before the APS. The flexibility of process gives the largest possibility in aeronautics, gas turbine, medical field and other applications using different parameters, deposited and target materials. Low pressure plasma spraying (LPPS) is considered with some particular features so the range of pressure is about 10- 250 mbar, the dimensions of the plasma jet and its homogeneity are important. The adaptation of modern pumping and control systems allow to reduce the worked pressure to 0,1 mbar and to have conditions close to physical vapour deposition (PVD). This paper presents the results of the deposition of a copper alloy powder using the very low pressure plasma spraying performed by a new system developed in the LERMPS
Shock Wave Physical Mechanisms of Modulated Arc as Applied to Dusted Plasma Flows to Form the Coatings
Authors: Gutman-Goodman B.B.
Published: August 2022

This work is an attempt to understand the physical mechanisms lying on the basis of using DC torch modulation technology for spraying. The influence of the plasma disturbances created by means of arc current modulation and an influence of these disturbances on thermodynamic parameters and dynamic viscosity of the modulated plasma jet are carried out. Thus, the phenomena providing modulation effects, both as in the plasmatron itself as well as in the mechanisms influencing on the plasma technology parameters have become understandable. It was shown, that inserting hydrocarbons into the air plasma jet conduces to transition of the torch with vortex stabilization of the arc to the laminar spraying mode with a high coefficient use of powder. The obtained physical estimations are used for explanation of the coatings sprayed characteristics. In the article are described shortly the advantages and shortcomings of Plasma Spraying Technology, HVOF, Cold Spraying, Plasma Spraying with Modulation, Detonation Technologies. Each technology has important features like high velocity of spraying particles, melted spraying material and non - melted spraying material. However, these technologies have rigid requirements in regard with a size of spraying powder or wire. In one case it is possible to neglect these requirements (in a certain degree) in the case of Plasma Technology with Modulation which is a combination of all advantages of the above mentioned technologies and was applied to military and space technique.
The Influence of Post Heat-Treatment on the Wear Properties of Nano-Structured WC-Co Coatings
Authors: Kim J.H. , Baik K.H. , Seong B.G. , Hwang S.Y.
Published: August 2022

The potential of post heat-treatment to improve the wear properties of nanostructured WC-Co coatings was investigated in the present study. Since the nanostructured coatings are more susceptible to the detrimental reactions during spraying than their conventional counterparts, there is certain limitation in optimization of coating properties by adjusting process parameters. Post heat-treatment of nanostructured coatings can thus offer one solution to achieve further improvement in coating performance. Nanostructured WC-Co coatings prepared by HVOF spraying were heat-treated under various temperatures and their wear properties were compared to those of the as-sprayed condition. The influence of the post heat-treatment was discussed in terms of changes in microstructure, composition and hardness of the coatings. These results demonstrate that the wear resistance of the nanostructured WC-Co coatings can be improved without any degradation of the substrate properties by proper post heat-treatment process.
Microstructural Observation of the Sintering Behavior of Nanostructured Yttria Stabilized Zirconia
Authors: Racek O. , Berndt C.C. , Guru D. , Heberlein J.
Published: August 2022

Multilayer thermal barrier coatings are being investigated for high temperature applications by employing a strain accommodating interlayer. Plasma sprayed coatings of nanostructured feedstock have shown promise in this direction. Layers of nanostructured yttria stabilized zirconia (nano–YSZ) and conventional YSZ were deposited on mullite substrates using the triple torch plasma reactor (TTPR), and on NiCrAlY coated steel substrates using the Praxair SG-100 plasma torch. The coatings were heat treated and the microstructure evaluated. Heat treating the samples lead to the formation of larger pores with a significant proportion of partially molten particles. The porosity evolved from the partial sintering of the nano-agglomerates. Porosity change during the sintering process was measured and the microstructure observed using electron microscopy. The nanostructured coatings were compared to conventional YSZ coatings.
A Computational Heat and Mass Transfers Model for a Laser Pyrolysis Reactor
Authors: Amara M. , El Ganaoui M. , Hourlier D.
Published: August 2022

Recently the research about technical ceramics knows a renewed interest. The synthesis process of nanopowders plays a significant role in the production of such materials. This work, concerns particularly the synthesis of the nanopowders by laser pyrolysis. A numerical model is developed in order to understand the influence of the heat transfers occurring in the reactor and around the reaction zone, for a better control of the process. The study highlights the importance of the thermal transfer in the cell. A simple one dimensional analysis enabled us to define a stability condition of the flame function of the precursor flow rate and the cell pressure. The extended 3D calculations underline the complex fluid flow and heat transfer developing in the synthesis reactor.
Plasma Sprayed Oxide Surfaces in Aqueous Environments
Authors: Harju M. , Mäntylä T. , Areva S. , Järn M. , Halme J. , Rosenholm J.B.
Published: August 2022

Plasma sprayed oxide coatings are widely used in applications where the surface properties of the coatings dictate the performance of the coating. The knowledge of chemical surface properties of plasma sprayed oxide coatings is very limited and to our knowledge surface chemical studies of these coatings have not been published. Surface properties of common plasma sprayed oxide coatings exposed to water based electrolytes were evaluated using several surface sensitive techniques such as X-ray photoelectron spectroscopy (XPS) and electrophoretic mobility studies. The dissolution behaviour of the coating materials were studied using inductively coupled plasma-mass spectroscopy (ICP-MS). Other characterization techniques included X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS). The correlation between chemical stability, bulk and surface properties of the coatings were evaluated. Obtained results are compared with published values of traditionally manufactured oxide counterparts.
Cermet Coating by APS : Influence of the Ceramic Phase and the Particle Size Range on the Mechanical Properties
Authors: Syed A.A. , Denoirjean A. , Grimaud A. , Fauchais P. , Girardin D.
Published: August 2022

The cermet coatings constituted by a metallic phase mixed with a ceramic one allows obtaining coating properties with a wide range of variations. This is particularly interesting for graded coatings produced by APS technique with two different injection ports devoted to each kind of powder. By monitoring the powder feed rates independently it is relatively easy to obtain the requested composition and also the gradient as a function of the coating thickness. In the present work 600 ìm graded coatings were produced with 5 or 6 layers, each one with a specific composition. The hardness properties of the whole coating were evaluated by the Knoop technique. Also each layer was produced separately and characterized as well. These coatings were devoted to thermo-mechanical applications. In this work the metallic phase is always NiCr 80/20 wt% and the ceramic phase is zirconia doped with yttria or ceria as well as Al2TiO5. The powders used as a standard have a size range included between 40 and 10 µm. Smaller size ranges were evaluated to produce NiCr / ZrO2, Y2O3 graded coatings and were compared to those obtained with the standard powder. In this last part a post heat treatment of the coating was evaluated against the mechanical properties.
Proporties of Thermally Sprayed Coatings on Magnesium Parts for Enhamcement of Wear and Corrosion Resistance
Authors: Lugscheider E. , Parco M. , Bach Fr.-W. , Möhwald K. , Engl L.
Published: August 2022

The technical and economical potential of innovative materials is gaining growing interest for technologically orientated companies. The use of lightweight materials is an extremely important consideration, especially when designing moving components (e. g. in aerospace, automotive or machine construction). Magnesium is a promising alternative to other lightweight materials, such as aluminum and titanium, due to its relatively high specific strength and stiffness. Further advantages are high thermal conductivity and good joining and machining capabilities. However, the use of magnesium alloys is restricted by relatively poor wear behavior and corrosion resistance. In order to overcome the limitations associated with magnesium alloys, a project was founded by the Materials Science Institute (MSI), at the RWTH Aachen, and the Institute of Materials Science (IW), at the University of Hannover, to deal with the application of wear and corrosion protective coatings on Mg alloys by means of thermal spraying. A variety of coating materials were applied on Mg substrates using several thermal spray processes (like Arc Spray and HVOF). The coatings were then characterized particularly with regard to their wear and corrosion properties. To further enhance the overall corrosion resistance two additional approaches were investigated. On the one hand various duplex coating systems were designed and applied. With the objective of decreasing the open porosity coatings were either densified by shot peening or sealed by applying organic sealers on the other hand.
Impact Behaviour of HVOF-Sprayed WC-CoCr Coatings
Authors: Reisel G. , Steinhäuser S. , Wielage B. , Hockauf M. , Meyer L.W.
Published: August 2022

In some applications like car armouring for personal safety, in bulk containers in pebbles working, in off-shore applications or in offroad-vehicles, impact of bodies with different sizes and high velocities has to be calculated in material design. A possibility to design under economical aspects is to use to low-cost material as substrate with a protective coating on its surface instead of using expensive bulk materials. One conceivable material system to be used as protective coating is WC-CoCr, which is usually applied by HVOF and shows high hardness combined with a good toughness of the matrix. These properties are very important for dissipation of the impact energy and for high fracture toughness. In the presented case study, WC-CoCr coatings with different carbide sizes were produced with the JP5000 system from TAFA. Projectiles with high velocities of more than 250 m/s were shot by an experimental shooting device on the coatings and for comparability on the uncoated substrate. Impact tests were done with balls and cylinders with varying impact angles between 10° and 90°. The powders and the coatings were characterized by means of microscopy and XRD. Furthermore, the hardness of the coatings was measured. After impact tests, the coatings were investigated with optical microscopy. In the case of ball impact, a significant dependency can be found between the impact behaviour and carbide size. Coatings with coarse carbides show the lowest impact depth. The dependency of the impact depth of coatings with one carbide size on their hardness level is relatively low. No dependencies of the carbide size or the hardness level can be found for impact with cylinders.
Influence of the Grit Blasting Process on the Properties of Thermally Sprayed Coatings
Authors: Buchmann M. , Fischer M. , Spence D. , Wenzelburger M. , Riegert-Escribano M.J. , Gadow R.
Published: August 2022

The quality and operation performance of layer composites manufactured by thermal spraying is influenced by two different processes, the activation process of the surface prior to coating deposition and the coating process itself. The activation of the substrate surface is mainly performed by grit blasting operations. Surface activation by grit blasting is used in order to improve the bonding between substrate and coating, which is strongly related to the size and nature of the surface topography and roughness generated by the blasting process. Besides the roughening effect, grit blasting induces compressive residual stresses into the substrate surface which can be critical especially for thin walled components, e.g. piston rings, where the component shape is an important factor for the operation behavior and functionality. Another effect is an increase of hardness in the surface region related to the induced compressive stresses. A variety of blasting parameters can influence the surface characteristics, like nozzle diameter, grit medium and size, blasting pressure, distance and time. The influence of these parameters on the surface roughness, hardness, component deformation and residual stresses was investigated by tactile surface metrology, universal hardness and Almen tests as well as experimental residual stress analysis with the incremental hole drilling and milling method. All investigations were performed on rectangular steel strips. The results are discussed concerning quality control features for grit blasting processes in serial production.
Stress-Relaxation and Creep Behavior of Heat-Treated Stand-Alone Plasma-Sprayed 7 wt.% Y2O3-ZrO2 Coatings
Authors: Petorak C.A. , Bowman K.J. , Trice R.W.
Published: August 2022

Plasma-sprayed 7 wt.% Y2O3-ZrO2 (YSZ) stand-alone coatings were subjected to 10, 50 and 100-hr heat treatments at 1200°C, followed by mechanical testing in compression at 25°C, 1050°C, and 1200°C. The mechanical tests performed on the samples included cyclic loading/ unloading, stress-relaxation, and creep. In cyclic compression tests at 25°C, it was observed that the YSZ coating that had been heat-treated for 50-hr at 1200°C demonstrated a higher modulus and more strain hysteresis as compared to an as-sprayed sample. As heat-treatment time increased, the YSZ stand-alone coating demonstrated less relaxation of the initial applied stress for stress-relaxation tests run at 1050°C and 1200°C. The steady-state creep rate was observed to decrease with increasing heat-treatment time prior to testing; as expected, the steady-state creep rate increases when the testing temperature was increased from 1050°C to 1200°C. Density (via Archimedes’) and phase analysis (via X-ray diffraction) were performed on YSZ coatings before (i.e. as-sprayed) and after heat-treating at 1200°C. Porosity was observed to decrease only slightly (~1%) after a 100-hr heat-treatment at 1200°C as compared to the as sprayed porosity. The high-yttria metastable tetragonal phase observed in the as-sprayed coatings was observed after a 100-hr heat-treatment at 1200°C. The same metastable tetragonal phase was also observed after a 100-hr heat-treatment at 1200°C followed by a 3-hr stress-relaxation test at 1200°C.