Capturing the Influence of Jet Fluctuations on Particles in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
H. Heinemann ◽  
A. O‘Brien
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
High Sensitivity ◽  
Plasma Jet ◽  
Plasma Generator ◽  
Operating Conditions ◽  
High Temporal Resolution ◽  
Cathode Plasma ◽  
Novel Method ◽  
Plasma Sprayed

Abstract Instabilities and fluctuations of the plasma jet can have a significant influence on the particle in-flight temperatures and velocities, thus affecting the properties of plasma sprayed coatings. Presented in this paper is a novel method for capturing the effects particles are exposed to in the plasma spraying process. High-speed camera images of a plasma jet generated by a cascaded three cathode plasma generator (TriplexPro-210) are recorded for varying operating conditions. The images are processed using the inverse Abel transform. This transformation accounts for the fact that the images represent a 2-D projection and generates correct intensity values of the plasma jet images. These images are then combined with particle tracks resulting from CFD simulations of the plasma jet to match the particles path with the recorded plasma jet. This new method allows a precise description of the plasma intensity experienced by individual particles with a high temporal resolution. The results show a high sensitivity of the method, it can even detect the influence of the plasma jet originating from the cascaded triple arc plasma generator, which is considered as rather stable, on the particles.

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

Influence of the Variation of Plasma Torch Parameters on Particle Melting and Solidification

1997 ◽  
Author(s):  
M. Vardelle ◽  
P. Fauchais ◽  
A. Vardelle ◽  
A.C. Léger
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Gas Flow ◽  
Operating Conditions ◽  
Characteristic Parameters ◽  
Powder Mass ◽  
Arc Current ◽  
Plasma Sprayed ◽  
Carrier Gas Flow ◽  
Melting And Solidification

Abstract A study of the flattening and cooling of particles plasma-sprayed on a substrate is presented. The characteristic parameters of the splats are linked to the parameters of the impacting particles by using an experimental device consisting of a phase Doppler particle analyzer and a high-speed pyrometer. However, during the long experiments required to get reliable correlations, it was observed that variations in plasma spray operating conditions may alter the particles behavior in the plasma jet. Therefore, a simple and easy-to-use system was developed to control in real time the spray jet. In this paper, the effect of carrier gas flow rate, arc current and powder mass flow rate is investigated. The results on zirconia and alumina powders show the capability of the technique to sense the particle spray position and width.

Novel Zro2-Mullite Composites Produced by Plasma Spraying

1998 ◽  
Author(s):  
K.A. Khor ◽  
Y. Li
Keyword(s):  
Plasma Spraying ◽  
Structural Integrity ◽  
Plasma Jet ◽  
Distilled Water ◽  
Composite Powders ◽  
Plasma Flame ◽  
Amorphous Phases ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Abstract Zirconia can induce enhanced fracture toughness to a number of ceramics when introduced as a reinforcement either in the form of particulates, dispersed phase or whiskers because of its unique tetragonal-monoclinic (t-*m) transformation. This paper presents the preparation of Zr0 2 reinforced mullite by plasma spraying a mixtures of zircon and alumina. The dissociation of zircon into zirconia and silica in a plasma flame is well-known. Pre-mixed powders of zircon and alumina are injected into a dc plasma jet. The plasma sprayed particles are collected in distilled water and analyzed. The results indicate that the plasma sprayed powders consist of zirconia, zircon and alumina. It was found that fine, mostly amorphous and chemically homogeneous composite powders can be obtained by ball milling and plasma spraying. Recrystallization of amorphous phases and formation of mullite occurred at about 1000 °C in plasma sprayed powders. This value is more than 500 °C lower than the formation of mullite in as-milled powders. Uniform coatings with good structural integrity were obtained by plasma spraying. The amount of amorphous phases was much higher in plasma sprayed coatings than in spheroidized powders, and the relative quantity of mullite in coatings after heat treatment is about 4 times as much as that obtained in the spheroidized powders.

A Computational Examination of the Sources of Statistical Variance in Particle Parameters During Thermal Plasma Spraying

2000 ◽  
Author(s):  
R.L. Williamson ◽  
J.R. Fincke ◽  
C.H. Chang
Keyword(s):  
Particle Size ◽  
Plasma Spraying ◽  
Thermal Plasma ◽  
Plasma Jet ◽  
Operating Conditions ◽  
Injection Velocity ◽  
Valuable Insight ◽  
Thermal Plasma Spraying ◽  
Particle Parameters ◽  
Statistical Variance

Abstract Computational modeling is used to systematically examine many of the sources of statistical variance in particle parameters during thermal plasma spraying. Using the computer program LAVA, a steady-state plasma jet typical of a commercial torch at normal operating conditions, is first developed. Then, assuming a single particle composition (ZrO2) and injection location, real world complexity (e.g., turbulent dispersion, particle size and density, injection velocity and direction, etc.) is introduced "one phenomenon at a time" to distinguish and characterize its effect and enable comparisons of separate effects. A final calculation then considers all phenomena simultaneously, to enable further comparisons. Investigating each phenomenon separately provides valuable insight into particle behavior. For the typical plasma jet and injection conditions considered, particle dispersion in the injection direction is most significantly affected by (in order of decreasing importance): particle size distribution, injection velocity distribution, turbulence, and injection direction distribution or particle density distribution. Only the distribution of injection directions and turbulence affect dispersion normal to the injection direction, and are of similar magnitude in this study. With regards to particle velocity and temperature, particle size is clearly the dominant effect.

High Speed Nailing for Bone Fracture Fixation: A Finite Element Penetration Model to Examine Nail Tip Design

2011 ◽  
Author(s):  
Matthew P. Prygoski ◽  
Steven R. Schmid
Keyword(s):  
Bone Fracture ◽  
Fracture Fixation ◽  
High Speed ◽  
Small Diameter ◽  
Fracture Site ◽  
Operating Conditions ◽  
Surgical Time ◽  
Pilot Hole ◽  
Bone Fragments ◽  
Novel Method

A novel method of bone fracture fixation has been proposed in which small-diameter bioresorbable nails/pins are inserted across the fracture site using a device similar to that of a pneumatic nail gun [1]. Multiple nails inserted at varying angles can prevent translation and rotation of any bone fragments allowing healing to progress uninhibited. High velocity insertion would reduce surgical time; the nail would create its own entry incision so a drilled pilot hole would be unnecessary. A self-contained nailer, preloaded with sterile nail cartridges, could improve surgical outcomes in non-ideal operating conditions such as those encountered in military field hospitals. The bioresorbable nature of the pins would also mitigate the need for potentially risky removal surgery [1].

scholarly journals Diagnostics for advanced materials processing by plasma spraying

2005 ◽  
Vol 77 (2) ◽  
pp. 443-462 ◽  
Author(s):  
C. Moreau ◽  
J.-F. Bisson ◽  
R. S. Lima ◽  
B. R. Marple
Keyword(s):  
Substrate Temperature ◽  
Plasma Spraying ◽  
Operating Conditions ◽  
Diagnostic Tools ◽  
Spray Parameters ◽  
Production Environment ◽  
Coating Properties ◽  
Industrial Sectors ◽  
Plasma Sprayed ◽  
Jet Characteristics

Advanced coatings deposited by plasma spraying are used in a large variety of industrial applications. The sprayed coatings are employed typically in industry to protect parts from severe operating conditions or to produce surfaces with specific functions. Applications are found in many industrial sectors such as aerospace, automobile, energy generation, and biomedical implants.Coatings are built by the successive deposition of molten or partially molten particles that flatten and solidify upon contact on the substrate, forming lamellae. The coating properties are intimately linked to the properties of these lamellae, which in turn depend on in-flight particle properties as well as substrate temperature during spraying. Consequently, the development of diagnostic tools for monitoring and controlling these spray parameters will help provide the necessary information to study the coating formation process, optimize the coating properties, and, eventually, control the spray process in production.In this paper, a review of some recent developments of optical diagnostic techniques applied to monitor plasma-sprayed particles is presented. In the first part of the paper, two different sensing techniques for in-flight particle measurement are described. First, time-resolved diagnostics on individual particles is described. This technique is used to study the instabilities of the particle characteristics associated with the plasma fluctuations. Secondly, a technique adapted for use in an industrial production environment for measuring the particle jet characteristics as an ensemble is presented. In the second part of the paper, the use of an optical system to study the influence of the substrate temperature on the flattening and solidification of sprayed particles impacting on a flat substrate is described. The last part of this paper describes the optimization of nanostructured coatings based on a tight control of the temperature and velocity of the plasma-sprayed particles.

Electron microscopy studies of plasma-sprayed materials

1983 ◽  
Vol 41 ◽  
pp. 70-71
Author(s):  
K.R. Subramanian ◽  
A.H. King ◽  
H. Herman
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface ◽  
Flame Temperature ◽  
Ceramic Coatings ◽  
Metallic Substrates ◽  
Hot Plasma ◽  
Almost All ◽  
Plasma Sprayed ◽  
Hostile Environments ◽  
Plasma Spraying Process

Plasma spraying is a technique which is used to apply coatings to metallic substrates for a variety of purposes, including hardfacing, corrosion resistance and thermal barrier applications. Almost all of the applications of this somewhat esoteric fabrication technique involve materials in hostile environments and the integrity of the coatings is of paramount importance: the effects of process variables on such properties as adhesive strength, cohesive strength and hardness of the substrate/coating system, however, are poorly understood.Briefly, the plasma spraying process involves forming a hot plasma jet with a maximum flame temperature of approximately 20,000K and a gas velocity of about 40m/s. Into this jet the coating material is injected, in powder form, so it is heated and projected at the substrate surface. Relatively thick metallic or ceramic coatings may be speedily built up using this technique.

D.C. Plasma Spraying: Effect of Arc root Fluctuations on Particle Behavior in the Plasma Jet

1999 ◽  
Vol 3 (2-3) ◽  
pp. 235-254 ◽  
Author(s):  
B. Dussoubs ◽  
G. Mariaux ◽  
Armelle Vardelle ◽  
Michel Vardelle ◽  
Pierre Fauchais
Keyword(s):  
Plasma Spraying ◽  
Plasma Jet ◽  
Particle Behavior ◽  
Arc Root

Rapid Online Buffer Exchange: A Method for Screening of Proteins, Protein Complexes, and Cell Lysates by Native Mass Spectrometry

2019 ◽  
Author(s):  
Zachary VanAernum ◽  
Florian Busch ◽  
Benjamin J. Jones ◽  
Mengxuan Jia ◽  
Zibo Chen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Speed ◽  
Structural Information ◽  
Protein Complexes ◽  
High Sensitivity ◽  
Native Mass Spectrometry ◽  
Structural Features ◽  
Consumer Products ◽  
Cell Lysates ◽  
Protein Expression And Purification

It is important to assess the identity and purity of proteins and protein complexes during and after protein purification to ensure that samples are of sufficient quality for further biochemical and structural characterization, as well as for use in consumer products, chemical processes, and therapeutics. Native mass spectrometry (nMS) has become an important tool in protein analysis due to its ability to retain non-covalent interactions during measurements, making it possible to obtain protein structural information with high sensitivity and at high speed. Interferences from the presence of non-volatiles are typically alleviated by offline buffer exchange, which is timeconsuming and difficult to automate. We provide a protocol for rapid online buffer exchange (OBE) nMS to directly screen structural features of pre-purified proteins, protein complexes, or clarified cell lysates. Information obtained by OBE nMS can be used for fast (<5 min) quality control and can further guide protein expression and purification optimization.

scholarly journals Automatic Dissolution Testing with High-Temporal Resolution for Both Immediate-Release and Fixed-Combination Drug Tablets

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Zhongmei Chi ◽  
Irfan Azhar ◽  
Habib Khan ◽  
Li Yang ◽  
Yunxiang Feng
Keyword(s):  
High Speed ◽  
Sequential Analysis ◽  
Immediate Release ◽  
Drug Dissolution ◽  
High Temporal Resolution ◽  
Dissolution Profile ◽  
Dissolution Testing ◽  
Combination Drug ◽  
Efficient Separation ◽  
High Efficient

AbstractDissolution testing plays many important roles throughout the pharmaceutical industry, from the research and development of drug products to the control and evaluation of drug quality. However, it is a challenging task to perform both high-efficient separation and high-temporal detection to achieve accurate dissolution profile of each active ingredient dissolved from a drug tablet. In our study, we report a novel non-manual-operation method for performing the automatic dissolution testing of drug tablets, by combining a program-controlled sequential analysis and high-speed capillary electrophoresis for efficient separation of active ingredients. The feasibility of the method for dissolution testing of real drug tablets as well as the performance of the proposed system has been demonstrated. The accuracy of drug dissolution testing is ensured by the excellent repeatability of the sequential analysis, as well as the similarity of the evaluation of dissolution testing. Our study show that the proposed method is capable to achieve simultaneous dissolution testing of multiple ingredients, and the matrix interferences can be avoided. Therefore it is of potential valuable applications in various fields of pharmaceutical research and drug regulation.

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