scholarly journals Analysis of Material Surface Renewal Technologies and Research of Laser Cladding Technology

2020 ◽  
Author(s):  
◽  
Andris Ratkus
Keyword(s):  
Laser Cladding ◽  
Mathematical Expression ◽  
Internal Surface ◽  
Material Surface ◽  
Technological Parameters ◽  
Surface Renewal ◽  
Power Intensity ◽  
Melt Pool ◽  
Coated Materials ◽  
Hardness Values

as made the technology more mainstream across a wider swathe of industries. Based on these industrial activities and the need for modification of metal coatings, a doctoral thesis has been developed with the theme: “Analysis of Material Surface Renewal Technologies and Research of Laser Cladding Technology”. The aim of the thesis is to clarify the influence of technological parameters and conditions on the characteristics of the coating obtained and to develop the mathematical expression for predicting the characteristics of the technologies for creating a layer of material. In addition, the following tasks have been defined: to undertake cladding experiments and analysis of the results by determining the dependence of the laser cladding characteristics on the cladding position and nozzle angle; to test the hardness of the coating and to determine the factors affecting the hardness in laser cladding; to give recommendations on the practical application of the technology for the restoration of both external and internal surface materials. The analysis of the technology for applying layers of material, the identification of the most important characteristics of the cladding, the development of experiments and the analysis of the results were performed in this work. It has been determined that the main technological advantages of quality and universality of products are achieved by means of laser cladding, which makes it possible to create small, local cladding. It has been assumed that the characteristics of the coating largely depend on the amount of material conveyed to the coating area which, in turn, is affected by the material feed rate and the speed of cladding. It has been experimentally confirmed that laser cladding technology is possible for all cladding positions, but the change of the position of the cladding, along with the nozzle angle, affects the flow of the material and the power intensity, which causes changes in the geometry of melt pool and affects the values of the coating characteristics, including its mechanical qualities. The hardness values of the laser coated materials have been determined and it was concluded that the nozzle angle, nozzle position, the shape of the laser point, the degree of coalescence of the cladding and the melt pool temperature all influence the hardness values of the cladding. In turn, the distribution of the temperature of the melt pool describes the nature of the hardness values of the cladding profile. Mathematical expressions have been developed in this work, to describe the characteristics of the laser cladding, with the introduction of a new laser cladding impact parameter that includes all the technological parameters used. The developed mathematical expression significantly improves the predictability of the technology and its application in production, in order to shorten the time of operation and improve the quality of the product. The results obtained are important for more extensive research and development in the field. The work provides valid recommendations for the practical realization of cladding.

Modeling and Experiments of Laser Cladding With Droplet Injection

2005 ◽  
Vol 127 (9) ◽  
pp. 978-986 ◽  
Author(s):  
J. Choi ◽  
L. Han ◽  
Y. Hua
Keyword(s):  
Fluid Flow ◽  
Laser Cladding ◽  
Dynamic Motion ◽  
Cladding Layer ◽  
Melt Pool ◽  
Material Deposition ◽  
Modeling And Experiments ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
The Impact

Laser aided Directed Material Deposition (DMD) is an additive manufacturing process based on laser cladding. A full understanding of laser cladding is essential in order to achieve a steady state and robust DMD process. A two dimensional mathematical model of laser cladding with droplet injection was developed to understand the influence of fluid flow on the mixing, dilution depth, and deposition dimension, while incorporating melting, solidification, and evaporation phenomena. The fluid flow in the melt pool that is driven by thermal capillary convection and an energy balance at the liquid–vapor and the solid–liquid interface was investigated and the impact of the droplets on the melt pool shape and ripple was also studied. Dynamic motion, development of melt pool and the formation of cladding layer were simulated. The simulated results for average surface roughness were compared with the experimental data and showed a comparable trend.

Geometry Modelling of Clads Generated by Laser Cladding

2012 ◽  
Vol 713 ◽  
pp. 85-90
Author(s):  
I. Tabernero ◽  
Aitzol Lamikiz ◽  
Eneko Ukar ◽  
S. Martínez
Keyword(s):  
Laser Cladding ◽  
Particle Concentration ◽  
Cfd Model ◽  
Melt Pool ◽  
Laser Cladding Process ◽  
The Finite Difference Method ◽  
Input Variables ◽  
Minimum Heat ◽  
Pool Area ◽  
Deposition Techniques

The laser cladding process is based on the generation of a melt-pool in a substrate where a filler material is injected, generating a high quality clad with a minimum heat affected zone. This process is industrially used to generate coatings over wear or damaged surfaces, being an alternative to traditional deposition techniques. One of the most important aspects for its industrial application is to know the clad geometry in order to calculate the deposited layer thickness. This work presents a model in which, starting from the concentration of injected material and the melt-pool geometry, clad height is finally estimated. Both input variables are obtained by two previous validated models. On one hand, the melt pool is estimated by a thermal model based on the finite difference method, and on the other hand, concentration of injected material is provided by a particle concentration CFD model. This data is used in a mass balance over melt-pool area in order to estimate the deposited clad height.

Assessment of Microstructure and Mechanical Properties in Laser Cladding, Welding and Surface Polishing Through Online Monitoring of Thermal History

2019 ◽  
Author(s):  
Ashish Kumar Nath ◽  
Muvvala Gopinath
Keyword(s):  
Mechanical Properties ◽  
Laser Cladding ◽  
Thermal History ◽  
Thermal Stresses ◽  
Ceramic Coating ◽  
Online Monitoring ◽  
Laser Polishing ◽  
Melt Pool ◽  
On Line ◽  
Repeatability And Reproducibility

Abstract Monitoring and controlling the microstructure, phases, and thermal stresses in laser cladding of materials which determine their mechanical properties is essential for ensuring repeatability and reproducibility in refurbishing engineering parts and building functional parts by layer-by-layer deposition in additive manufacturing process. Several studies have been reported on on-line monitoring of temperature, melt-pool geometry, and porosity etc. in laser powder deposition process, but only a few on the assessment of solidification morphology, microstructure, and thermal stresses. Since these features are dictated by the melt-pool lifetime, cooling and solidification rates, their effects on the evolution of microstructure and the state of ceramic particles in laser deposition of Ni-super alloy and metal matrix composites of WC and TiC are investigated in the current study. Good correlation exists between the thermal history monitored online and the solidification characteristics. Process maps based on the melt-pool lifetime as a function of laser cladding parameters for these materials are developed. On-line monitoring of thermal cycle is extended to laser welding of stainless steel and titanium which are difficult to join together due to the formation of brittle intermetallic phases, and laser polishing of thermal sprayed ceramic coating to develop a better understanding and control of these processes. Melt-pool lifetime is found to have significant effect on the crack growth in fusion welding and by optimizing the former the later could be mitigated. Similarly, the cooling rate in laser polishing of thermal sprayed ceramic coating is found to have significant influence on the surface roughness and residual stress. These studies show that the online monitoring of thermal history can be exploited for controlling the process quality and ensuring the repeatability and reproducibility in different laser material processing modalities.

Tungsten Inert Gas Surface Alloying of Commercial Purity Titanium (CP-Ti) with Fe-C-Si Ternary Mixtures

2014 ◽  
Vol 1024 ◽  
pp. 207-210 ◽  
Author(s):  
S.A. Adeleke ◽  
M.A. Maleque
Keyword(s):  
Surface Modification ◽  
Energy Input ◽  
Ternary Mixtures ◽  
Material Surface ◽  
Commercial Purity ◽  
Dendritic Microstructure ◽  
Melt Pool ◽  
Commercial Purity Titanium ◽  
Cp Ti ◽  
Purity Titanium

Surface modification by means of alloying is a vital process to improve the performance of a material surface which is subjected to wear and corrosion environments without altering the bulk properties. In this study, the surface of commercial purity-titanium (CP-Ti) material was alloyed using pre-placed powder mixture of iron, silicon and carbon at different weight ratios under TIG torch melting technique. The effects of energy input (1080 and 1350 J/mm) in TIG torch on the melt geometry, topography, microstructure and hardness were examined. The results showed that the TIG torch produced melt pools geometry with hemispherical in shape and different geometrical dimensions. Pores were seen to be concentrated at the edges where low melting energies are prominent to entrapped escaped gases upon fast melt solidification. The melt layers with the 1350 J/mm consisted of armed typed of TiC precipitation in the presence of longer solidification time. The sizes of dendrites observed at energy inputs of 1350 J/mm was found to be greater in population and larger in the middle of the melt pool compared to the energy input of 1080 J/mm. The alloyed layer exhibited a maximum hardness of ~ 810 HV which is about 4 times greater than the base hardness of 200 HV. The high hardness observed at particular areas is attributed to the higher population and larger sizes of dendritic microstructure produced using 1350 J/mm TIG arc source compared to 1080 J/mm which was dominated by lesser precipitated TiC resulting lower hardness values in the melt pool. Keywords: Surface modification; TiC; TIG; dendrites; microhardness

Wear and Morphology Investigation of Cr/WC-Ni Based Composite Coating by Laser Cladding

2014 ◽  
Vol 1061-1062 ◽  
pp. 538-541
Author(s):  
Zhi Hong Dong ◽  
Hong Yuan Fan
Keyword(s):  
Magnetron Sputtering ◽  
Composite Coating ◽  
Laser Cladding ◽  
Die Steel ◽  
Hardness Tester ◽  
Coating Surface ◽  
Metallurgical Bonding ◽  
Spray Technique ◽  
The Matrix ◽  
Hardness Values

Cr/WC-Ni composite coating was prepared on Cr12MoV die steel by thermal spray technique, and then further treated using laser cladding technique. WC powders was coated Cr by D.C. magnetron sputtering method. The structure, composition, hardness, morphology were analyzed and measured by XRD and SEM and hardness tester. Tribological experiments were carried out on an abrasion machine. The results showed thatCr film prevented WC decomposition, and Cr/WC-Ni coating had the higher hardness values compared with WC-Ni coating. After the treatment with the laser cladding, the coating surface was uniform and compact and had no cracks, the boding between the matrix and coating surface had a good metallurgical bonding, and sub-surface showed a higher hardness.

The Depositional Laser Cladding with Fiber Laser

2009 ◽  
Vol 628-629 ◽  
pp. 447-452
Author(s):  
Peng Fei Lv ◽  
Ji Min Chen ◽  
F.R. Liu
Keyword(s):  
Particle Size ◽  
Laser Cladding ◽  
Surface Engineering ◽  
Laser Energy ◽  
Thin Layers ◽  
Material Surface ◽  
New Approach ◽  
Mean Particle Size ◽  
Cladding Layer

Laser cladding has been developed as a useful technology to modify material surface in industry. In this paper a new approach of surface modification is introduced. Depositional Laser Cladding (DLC) was developed and the different mechanisms were investigated during the manufacture. Basing on particular analysis of defects in the experiment, the relation between the quality of cladding layer and laser energy density is manifested. Depositional effect and thermal effect play their roles in different place and the depositional effect provides thin layers with the thickness of near mean particle size. Appropriate parameters of laser energy can promote high quality, avoiding pores and stacks in agglomeration and ebullition. Controllable low thickness near mean particle size and sharp edge make it possible to be used on producing certain shape in the surface engineering field, such as restoring and gradient materials.

scholarly journals Increasing efficiency of iron ore magnetic separation by using ultrasonic technologies

2021 ◽  
Vol 280 ◽  
pp. 08004
Author(s):  
Vladimir Morkun ◽  
Natalia Morkun ◽  
Vitalii Tron ◽  
Vladimir Golik ◽  
Arkadii Davidkovich
Keyword(s):  
Magnetic Separation ◽  
Iron Ore ◽  
Structural Parameters ◽  
High Energy ◽  
Material Surface ◽  
Technological Parameters ◽  
Magnetic Separator ◽  
Ultrasonic Methods ◽  
Dispersed Particles ◽  
Enhance Efficiency

The research is aimed at solving the topical problem of enhancing efficiency of iron ore magnetic separation by applying ultrasonic technologies to identify optimal technological parameters of magnetic separation, improving controlled structural parameters of a magnetic separator and pretreating slurry by highenergy ultrasound to clean the ore material surface from fine-dispersed particles of minerals and slime, as well as disintegrate ore aggregates fed to the magnetic separator. The main tasks involve identifying regularities of influence of slurry pretreatment by high-energy ultrasound on properties of iron ore magnetic separation, determining regulations of improving technological and controlled structural parameters of the magnetic separator using ultrasonic methods, developing and substantiating methods to enhance efficiency of iron ore magnetic separation by applying ultrasonic technologies.

scholarly journals Research on structure and technological parameters of multi-channel cold spraying nozzle

2021 ◽  
Vol 5 (1(113)) ◽  
pp. 6-14
Author(s):  
Wenjie Hu ◽  
Kun Tan ◽  
Sergii Markovych ◽  
Tingting Cao
Keyword(s):  
High Speed ◽  
Single Channel ◽  
Cold Spraying ◽  
Particle Collision ◽  
Powder Injection ◽  
Material Surface ◽  
Specific Reference ◽  
Technological Parameters ◽  
Internal Channel ◽  
Powder Spraying

Cold spraying technology is a method to obtain coating by the high-speed collision of particles with the substrate through supersonic (300–1200 m/s) propulsion gas. The deposition process is mainly mechanical bonding, which has attracted more and more attention in engineering applications. The critical component of a cold spraying system is the nozzle. The performance of the nozzle directly affects the quality of the material surface coating. Therefore, the discussion of the nozzle is of great significance. At present, there are many examples of cold spraying single-channel nozzles in engineering, but there are few reports about multi-channel cold spraying nozzles. This paper explores and studies the multi-channel cold spraying nozzle, designs a special three internal channel nozzle, and adopts a 90° angle in the divergent section of the nozzle. When spraying in a small area, the nozzle with angle has apparent advantages for spraying more areas. The powder injection pressure, particle size, recovery coefficient, and internal channel position are analyzed, which affect the particle trajectory. Combined with these factors, the multi-channel nozzle is optimized and improved to solve the problem of particle collision with the inner wall of the nozzle. Finally, the technological parameters of aluminum, titanium, copper, nickel, magnesium, and zinc powders are preliminarily studied using the multi-channel nozzle. The results show that the multi-channel nozzle meets the critical velocity requirements of copper, magnesium, and zinc powder spraying in the homogeneous (powder and matrix are the same material) and aluminum powder spraying in the case of heterogeneous (powder and matrix are different materials), the multi-channel nozzle has a sound engineering application prospect and provides a specific reference for relevant technicians.

scholarly journals THE INFLUENCE OF TECHNOLOGICAL PARAMETERS OF LASER SURFACING ON THE PROPERTIES OF NiCrBSiC-WC COMPOSITES

2018 ◽  
Vol 13 (4) ◽  
pp. 58-66
Author(s):  
A. E. Zatoka ◽  
D. V. Drobot ◽  
S. P. Merchev ◽  
S. V. Nevezhin ◽  
A. S. Gerasimov ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Service Life ◽  
Tungsten Carbide ◽  
Laser Cladding ◽  
Composite Coatings ◽  
Tungsten Carbides ◽  
Technological Parameters ◽  
Carbide Composite ◽  
Measurement While Drilling ◽  
Mechanical And Service Properties

It was investigated the influence of technological parameters of laser cladding on the thickness of the carbide composite coatings with similar composition and properties of matrix and different types of reinforcing inclusions (spherical tungsten carbides (WC) and recycled carbides). Special attention is paid to physical-mechanical and service properties of the composites such as hardness and resistance to abrasive wear. It is established that the thickness of the carbide composite coatings increases with increasing laser power and flow rate of the carrier gas, and with decreasing speed of the laser and the step of cladding. The study showed that at the addition of 50 wt.% WC matrix has smaller hardness values 540-560 HV, which allows to obtain the structure of the carbide composite coatings without cracks. At the same time, at addition of 80 wt.% WC matrix has higher hardness 670 HV, which does not provide the structure without cracks. Resistance of composites NiCrBSiC-WC to cracking, as well as their wear resistance, increases with increasing content of tungsten carbide. The wear resistance of the coatings received from powder Technicord 655-SL, with a reinforcement by recycled carbide, comparable to that for coatings from spherical tungsten carbide Tekmat WC-125. Coatings NiCrBSiCWC, obtained by laser cladding, are used to increase the service life of the equipment telemetering systems, in particular, it is possible to prevent of abrasion and provide of increasing the service life of the contact pads of the equipment for measurement while drilling.

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