scholarly journals Application of functional coatings by supersonic thermal plasma flows

2021 ◽  
Vol 2131 (5) ◽  
pp. 052053
Author(s):  
V I Kuzmin ◽  
I P Gulyaev ◽  
D V Sergachev ◽  
B V Palagushkin ◽  
O Y Lebedev
Keyword(s):  
Plasma Torch ◽  
High Speed ◽  
Laval Nozzle ◽  
Heating Temperature ◽  
Thermal Spraying ◽  
Functional Coatings ◽  
Melting Points ◽  
Supersonic Plasma ◽  
De Laval Nozzle ◽  
Injection Unit

Abstract Development of modern high-speed technologies for thermal spraying proves that deposition of high-quality dense coatings requires velocity of sprayed particles to be 600 m/s and above. Plasma spraying is the most versatile and highly productive deposition method of various functional coatings without any limitations on the melting points of the sprayed materials. Present work describes a DC plasma torch designed for operation in a supersonic mode. The supersonic plasma torch features de Laval nozzle, utilization of air as a plasma-forming gas, and annular injection unit for delivery of the powder to the plasma jet. The comparison of NiCr and NiAl coatings deposited both in subsonic and supersonic modes are presented. Methods for further increasing the sprayed particles’velocity and the requirements for their heating temperature are proposed.

An improved de Laval nozzle experiment

2021 ◽  
pp. 030641902110341
Author(s):  
Nicholas Goodman ◽  
Brian J Leege ◽  
Peter E Johnson
Keyword(s):  
Data Acquisition ◽  
Laval Nozzle ◽  
Flow Characteristics ◽  
Data Acquisition System ◽  
Isentropic Flow ◽  
Hands On ◽  
De Laval Nozzle ◽  
Physical Phenomena ◽  
The Impact ◽  
The Relationship

Exposing students to hands-on experiments has been a common approach to illustrating complex physical phenomena that have been otherwise modelled solely mathematically. Compressible, isentropic flow in a duct is an example of such a phenomenon, and it is often demonstrated via a de Laval nozzle experiment. We have improved an existing converging/diverging nozzle experiment so that students can modify the location of the normal shock that develops in the diverging portion to better understand the relationship between the shock and the pressure. We have also improved the data acquisition system for this experiment and explained how visualisation of the standing shock is now possible. The results of the updated system demonstrate that the accuracy of the isentropic flow characteristics has not been lost. Through pre- and post-laboratory quizzes, we show the impact on student learning as well.

scholarly journals Current Research Status on Cold Sprayed Amorphous Alloy Coatings: A Review

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 206
Author(s):  
Qiang Wang ◽  
Peng Han ◽  
Shuo Yin ◽  
Wen-Juan Niu ◽  
Le Zhai ◽  
...  
Keyword(s):  
High Temperature ◽  
Amorphous Alloy ◽  
Amorphous Alloys ◽  
Composite Coatings ◽  
Thermal Spraying ◽  
Functional Coatings ◽  
Research Status ◽  
Key Issues ◽  
Wear And Corrosion Resistance ◽  
Amorphous Coatings

Compared with traditional crystalline materials, amorphous alloys have excellent corrosion and wear resistance and high elastic modulus, due to their unique short-range ordered and long-range disordered atomic arrangement as well as absence of defects, such as grain boundaries and dislocations. Owing to the limitation of the bulk size of amorphous alloys as structural materials, the application as functional coatings can widely extend their use in various engineering fields. This review first briefly introduces the problems involved during high temperature preparation processes of amorphous coatings, including laser cladding and thermal spraying. Cold spray (CS) is characterized by a low-temperature solid-state deposition, and thus the oxidation and crystallization related with a high temperature environment can be avoided during the formation of coatings. Therefore, CS has unique advantages in the preparation of fully amorphous alloy coatings. The research status of Fe-, Al-, Ni-, and Zr-based amorphous alloy coatings and amorphous composite coatings are reviewed. The influence of CS process parameters, and powders and substrate conditions on the microstructure, hardness, as well as wear and corrosion resistance of amorphous coatings is analyzed. Meanwhile, the deposition mechanism of amorphous alloy coatings is discussed by simulation and experiment. Finally, the key issues involved in the preparation of amorphous alloy coatings via CS technology are summarized, and the future development is also being prospected.

Morphology of Edge Cracks of Rolled Magnesium Alloy Sheet

2014 ◽  
Vol 922 ◽  
pp. 469-474 ◽  
Author(s):  
Sho Manabe ◽  
Hiroshi Utsunomiya ◽  
Tetsuo Sakai ◽  
Ryo Matsumoto
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
High Speed ◽  
Heating Temperature ◽  
Thin Sheet ◽  
Contact Length ◽  
Alloy Sheet ◽  
Different Temperatures ◽  
Edge Cracks ◽  
Critical Reduction

Magnesium alloys show low deformability at low temperature because of hcp structure and inactiveness of basal slip. Manufacturing of thin sheet is difficult in industries. Some approaches, such as small-draft multi-pass rolling, intermediate annealing, isothermal rolling and high-speed rolling were proposed to overcome the deformability. However, small edge cracks are still formed on the sheet. In this study, rolling speed of 1000m/min was employed to warm-roll AZ31B magnesium alloy in a single pass at different temperatures. The edge cracks formed after the rolling were classified into three main groups: minor, regular and zigzag edge cracks. ‘Crack contact length’ are introduced to explain the morphology of edge cracks. The results show that the critical reduction for crack initiation depends on the pre-heating temperature. The spacing between edge cracks increases linearly with the crack contact length regardless of roll diameter, speed and reduction. It is suggested that this approach is useful to understand the formation mechanism of edge cracks and to evaluate the rollability of magnesium alloys.

scholarly journals Power Dissipation of an Inductively Coupled Plasma Torch under E Mode Dominated Regime

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 834
Author(s):  
Nan Yu ◽  
Renaud Jourdain ◽  
Mustapha Gourma ◽  
Fangda Xu ◽  
Adam Bennett ◽  
...  
Keyword(s):  
Power Dissipation ◽  
Inductively Coupled Plasma ◽  
Plasma Torch ◽  
Electrical Response ◽  
Inductively Coupled ◽  
De Laval Nozzle ◽  
Surface Fabrication ◽  
Icp Torch ◽  
Frequency Power

This paper focuses on the power dissipation of a plasma torch used for an optical surface fabrication process. The process utilizes an inductively coupled plasma (ICP) torch that is equipped with a De-Laval nozzle for the delivery of a highly collimated plasma jet. The plasma torch makes use of a self-igniting coil and an intermediate co-axial tube made of alumina. The torch has a distinctive thermal and electrical response compared to regular ICP torches. In this study, the results of the power dissipation investigation reveal the true efficiency of the torch and discern its electrical response. By systematically measuring the coolant parameters (temperature change and flow rate), the power dissipation is extrapolated. The radio frequency power supply is set to 800 W, E mode, throughout the research presented in this study. The analytical results of power dissipation, derived from the experiments, show that 15.4% and 33.3% are dissipated by the nozzle and coil coolant channels, respectively. The experiments also enable the determination of the thermal time constant of the plasma torch for the entire range of RF power.

Hybrid Induction Plasma Cutting Process - A New Technology for High Speed Metal Cutting

2014 ◽  
Author(s):  
Jerald E. Jones ◽  
Valerie L. Rhoades ◽  
Mark D. Mann ◽  
Todd Holverson
Keyword(s):  
Induction Heating ◽  
Plasma Torch ◽  
High Speed ◽  
Metal Cutting ◽  
New Technology ◽  
Cutting Process ◽  
Plasma Cutting ◽  
Air Plasma ◽  
Aircraft Carrier ◽  
Initial Development

A new cutting process, a hybrid system, uses induction heating to heat the metal ahead of the plasma cutting torch. The process has demonstrated the ability to plasma cut steel parts at speeds of up to 4X the speed of the plasma torch without the induction heating. Although the total heat input per unit time is greater, because of the increase in speed, the heat which is conducted into the cut pieces is less. This causes less potential metallurgical damage, less potential distortion, and reduced coating damage and reduced emissions during cutting, in comparison to the plasma cutting process without the induction heating. The initial development was primarily for use in cutting nuclear submarine and aircraft carrier hulls, for scrapping after decommissioning. The process has been demonstrated cutting steel plates and can be used in ship production as well. The primary motivation of the SBIR project was to reduce the heating of the cut pieces, in order to reduce the particulate matter (PM) emissions which occur when coated ship hull material is cut. An induction coil is positioned in front of the plasma cutting torch, to bring the material to an elevated temperature of at least 1600° F, before the plasma is applied to the metal surface. Induction heating testing has shown that the 35 kW induction system can maintain the 1600° F surface temperature at travel speeds of above 220 inches per minute on steel as thick as 3 inches. Once the steel is at that temperature an air plasma torch can cut the metal much faster than cutting cold steel.

scholarly journals Effect of Gas Pressure and Temperature on Stereometric Properties of Al+Al2O3 Composite Coatings Deposited by LPCS Method

2014 ◽  
Vol 59 (3) ◽  
pp. 879-886 ◽  
Author(s):  
M. Winnicki ◽  
T. Piwowarczyk ◽  
A. Małachowska ◽  
A. Ambroziak
Keyword(s):  
Laval Nozzle ◽  
Composite Coatings ◽  
Gas Pressure ◽  
Feedstock Powder ◽  
Substrate Distance ◽  
Al2o3 Composite ◽  
Spray Method ◽  
Powder Mass ◽  
De Laval Nozzle ◽  
Temperature And Pressure

Abstract The paper deals with effect of working gas pressure and temperature on surface stereometry of coatings deposited by low-pressure cold spray method. Examinations were focused on aluminium coatings which are commonly used to protect substrate against corrosion. A commercial Al spherical feedstock powder with admixture of Al2O3 (Al + 60vol.-% Al2O3), granulation -50+10 µm, was used to coat steel, grade S235JR. Thedeposited coatings were studied to determine their stereometry, i.e. roughness, transverse and longitudinal waviness, topography of surface and thickness as the functions of gas pressure and temperature. A profilometer and focal microscope were used to evaluate the stereometric properties. In order to reduce the number of variables, the remaining process parameters, i.e. shape and size of de Laval nozzle, nozzle-to-substrate distance, powder mass flow rate, linear velocity of spraying gun, were kept unchanged. The investigation confirmed influence of temperature and pressure on coating thickness as well as on the surface seterometry.

scholarly journals Coatings of Carbide-Metal Systems (Cr3C2-NiCr and WC-Co-Cr) Deposited by High-Velocity Atmospheric Plasma Spraying from Specially Modified Fine-Grained Powders

2018 ◽  
Vol 1 (1) ◽  
pp. 18-23
Author(s):  
Vadim Verlotski ◽  
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Deposition ◽  
Thermal Spraying ◽  
Atmospheric Plasma ◽  
Metal Particles ◽  
Fine Grained ◽  
Plasma Torches ◽  
Carbide Coatings ◽  
Gas Tight

In this article, the author poses and responds to a provocative question that has practically ceased to be asked in the field of thermal spraying of carbide coatings: Is the current worldwide trend of using only unmelted metal particles to form coatings (HVOF, HVAF and cold spray methods) correct, and is the deposition of completely melted powders (plasma spraying methods) really outdated? The results of high-speed plasma deposition of new carbide powders allowed the author to prove that only coatings from molten particles can solve the main problem of such coatings, namely the problem of permeability along the grain boundaries. Through the use of modern Axial III plasma torches combined with optimized fine-grained powders, it has been possible to create Cr3C2-NiCr as well as WC-Co-Cr gas-tight layers.

scholarly journals Magnetic Effects at the Edge of the Solar System: MHD Instabilities, the de Laval Nozzle Effect, and an Extended Jet

2004 ◽  
Vol 611 (1) ◽  
pp. 575-586 ◽  
Author(s):  
M. Opher ◽  
P. C. Liewer ◽  
M. Velli ◽  
L. Bettarini ◽  
T. I. Gombosi ◽  
...  
Keyword(s):  
Solar System ◽  
Laval Nozzle ◽  
Magnetic Effects ◽  
Mhd Instabilities ◽  
De Laval Nozzle

Novel Concept for Totally Integrated Automation (TIA) Using Siemens Bus System and WinCC Online Control

2000 ◽  
Author(s):  
T. Frederking ◽  
R. Gadow
Keyword(s):  
Process Parameters ◽  
High Speed ◽  
Data Exchange ◽  
Thermal Spraying ◽  
Software Tool ◽  
Functionally Graded ◽  
Flame Spray ◽  
Total Quality ◽  
Spray Process ◽  
Bus System

Abstract Total quality management requires definite process control as well as online diagnostics, if applied in industrial surface refinement by thermal spraying. A concept for integrated online diagnostics for the high velocity oxygen fuel (HVOF) flame spray process is presented using Siemens S7-300 programmable logic controller and PC-based Siemens WinCC (Windows Control Center) visualization software. The standard functionality of the WinCC programming environment can be extended by C-scripts. The integrated database allows to protocol the relevant process parameters periodically for total quality assurance. Also particle flux imaging software tools can be implemented to adjust online process parameters and for process diagnostic purposes. The Siemens bus system hierarchy thereby provides high speed communication skills for field bus level data exchange and for supervising system components, e.g. CCD-cameras. The interconnection between S7-300 PLC, 6-axis-robot and a novel WinCC software tool enables definite automatic changes of recipes during the coating process to generate functionally graded coatings.

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