scholarly journals Properties of Curved Parts Laser Cladding Based on Controlling Spot Size

2020 ◽  
Vol 10 (2) ◽  
pp. 728 ◽  
Author(s):  
Haibo Huang ◽  
Wenlei Sun ◽  
Yong Huang ◽  
Jiangtong Yu
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Coating Thickness ◽  
Flaw Detection ◽  
Spot Size ◽  
Laser Spot ◽  
Reconstruction Method ◽  
Laser Head ◽  
Spline Surface ◽  
Curvature Sphere

In this study, a method based on controlling the laser spot size was proposed in the process of curved parts laser cladding, and the coatings obtained by this method were analysed through investigation of the microstructure, microhardness, adhesion property and wear resistance properties. The nonuniform rational B-spline surface (NURBS) reconstruction method was used to obtain the workpiece geometrical characteristics of laser cladding, and through the establishment of a mathematical model, the process of the laser beam working on the curved surface was simplified as the intersection of the cylinder and curvature sphere. Then, the spot size was transformed into the area of a cylinder intersecting with a sphere, and by adjusting the laser head, the size of the laser spot was controlled in the threshold and interpolation points were obtained. The laser cladding trajectory was ensured by these interpolation points, and the experiment was carried out to study the properties of the coating. The results showed that the average coating thickness was about 1.07 mm, and the fluctuation of coating thickness did not exceed 0.05 mm; also, there were no cracks or pores in the layer after penetrant flaw detection. The SEM showed that the grains passed through the transition of plane crystal, cellular crystal, dendrite and equiaxed crystal from the bottom to the top of the layer. After 30 cycles of thermal shock tests, the cladding layer was still well bonded with the substrate and the microhardness and wear resistance were 2 times and 1.4 times higher than that of substrate, respectively.

Modelling of the laser spot size dependence of retinal thermal damage

2005 ◽  
Author(s):  
Karl Schulmeister ◽  
Bernhard Seiser ◽  
Florian Edthofer ◽  
David J. Lund
Keyword(s):  
Size Dependence ◽  
Thermal Damage ◽  
Spot Size ◽  
Laser Spot ◽  
Laser Spot Size

Microstructure and Grain Abrasion Properties of Cr3C2-NiCr Coating Prepared by Laser Cladding Method

2012 ◽  
Vol 271-272 ◽  
pp. 3-7
Author(s):  
Long Wei ◽  
Zong De Liu ◽  
Xin Zhi Li ◽  
Ming Ming Yuan ◽  
Cheng Yuan Zhong
Keyword(s):  
Wear Resistance ◽  
Wear Rate ◽  
Laser Cladding ◽  
Micro Hardness ◽  
High Quality ◽  
Wear Resistant ◽  
Hardness Tester ◽  
Technology Analysis ◽  
Main Component

Cr3C2-NiCr has high quality of wear resistant properties and is widely used in abrasive environment. In this paper, Cr3C2-NiCr coating was prepared on 45 steel by laser cladding technology. Analysis and research of the coatings were achieved by SEM and XRD to determine the main component and the different region on coatings. The hardness and the element component were investigated by micro-hardness tester and EDS. Abrasion tests were performed to contrast the wear resistance of two materials. The results indicate that the hardness of the coatings is nearly 3 times as the substrate. The coatings are well combined with the substrate and the phase of Cr3C2 has a large proportion in the coatings. Abrasion tests show that the average of wear rate on substrate is 5.2 times as the coatings.

Diode Laser Cladding on A5052 Aluminium Alloy for Wear Resistance

2005 ◽  
Author(s):  
Shingo Iwatani ◽  
Yasuhito Ogata ◽  
Keisuke Uenishi ◽  
Kojiro F. Kobayashi ◽  
Akihiko Tsuboi
Keyword(s):  
Wear Resistance ◽  
Aluminium Alloy ◽  
Diode Laser ◽  
Laser Cladding ◽  
Co2 Laser ◽  
Reaction Layer ◽  
Heat Input ◽  
Aluminium Content ◽  
Alloy Substrate ◽  
Clad Layer

In order to improve a wear resistance of aluminium alloy, we proposed a diode laser cladding on the surface of a A5052 aluminium alloy. Firstly, an applicability of diode laser to laser cladding was evaluated. In this result, application of diode laser made it possible to obtain stable beads in low heat input compared with CO2 laser. According to the increase in aluminium content in the obtained clad layer, the microstructure of the clad layer changed as γ (8∼20%) → γ + α (10∼30%) → Fe3Al (30%∼). At the interface between the clad layer and the aluminium alloy substrate, the reaction layer consisting of Fe2Al5 and FeAl3 formed. In the abrasion wear the obtained clad layers exhibited a higher wear resistance compared with the aluminium alloy.

Fabrication of SiC Particulates Reinforced MoSi2 Composite Coating by Laser Cladding

2008 ◽  
Vol 373-374 ◽  
pp. 304-307
Author(s):  
Sen Yang ◽  
Ming Run Wang ◽  
Tao Gong ◽  
Wen Jin Liu
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Continuous Wave ◽  
Steel Substrate ◽  
Laser Output Power ◽  
Scanning Velocity ◽  
Sic Particulates ◽  
Metallurgical Bond ◽  
Improve Wear Resistance

In order to improve wear resistance of carbon steel, laser cladding experiments were carried out using a 3kW continuous wave CO2 laser. The diameter of the laser beam was 3-5mm, the scanning velocity was 3-10mm/s, and the laser output power was 1.0-1.3kW. The experimental results showed that MoSi2/SiCP composites coating could be in-situ synthesized from mixture powders of molybdenum, silicon and SiC by laser cladding. A good metallurgical bond between the coating and the substrate could be achieved. The microstructures of the coating were mainly composed of MoSi2, SiC and FeSiMo phases. The average microhardness of the coating was about HV0.21300, about 6.0 times larger than that of steel substrate.

scholarly journals Long lifetime of bialkali photocathodes operating in high gradient superconducting radio frequency gun

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. Wang ◽  
V. N. Litvinenko ◽  
I. Pinayev ◽  
M. Gaowei ◽  
J. Skaritka ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Electron Beams ◽  
Spot Size ◽  
Laser Spot ◽  
Laser Spot Size ◽  
High Quantum Efficiency ◽  
High Brightness ◽  
High Charge ◽  
Superconducting Radio Frequency ◽  
Long Lifetime

AbstractHigh brightness, high charge electron beams are critical for a number of advanced accelerator applications. The initial emittance of the electron beam, which is determined by the mean transverse energy (MTE) and laser spot size, is one of the most important parameters determining the beam quality. The bialkali photocathodes illuminated by a visible laser have the advantages of high quantum efficiency (QE) and low MTE. Furthermore, Superconducting Radio Frequency (SRF) guns can operate in the continuous wave (CW) mode at high accelerating gradients, e.g. with significant reduction of the laser spot size at the photocathode. Combining the bialkali photocathode with the SRF gun enables generation of high charge, high brightness, and possibly high average current electron beams. However, integrating the high QE semiconductor photocathode into the SRF guns has been challenging. In this article, we report on the development of bialkali photocathodes for successful operation in the SRF gun with months-long lifetime while delivering CW beams with nano-coulomb charge per bunch. This achievement opens a new era for high charge, high brightness CW electron beams.

MICROSTRUCTURES AND DRY SLIDING WEAR RESISTANCE OF THE LASER CERAMICS COMPOSITE COATING ON PURE Ti

2012 ◽  
Vol 19 (03) ◽  
pp. 1250017 ◽  
Author(s):  
PENG LIU ◽  
YUANBIN ZHANG ◽  
HUI LUO ◽  
YUSHUANG HUO
Keyword(s):  
Wear Resistance ◽  
Composite Coating ◽  
Laser Cladding ◽  
Dry Sliding Wear ◽  
X Ray Diffraction ◽  
Phase Constituent ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Modification Technique ◽  
Surface Performance

In this study, Al–Ti–Co was used to improve the surface performance of pure Ti . Laser cladding is an important surface modification technique, which can be used to improve the surface performance of pure Ti . Laser cladding of the Al–Ti–Co + TiB2 pre-placed powders on pure Ti can form ceramics reinforced the composite coating, which improved the wear resistance of the substrate. Characteristics of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness and wear tests. And the laser-cladded coating can also have major dilution from the substrate. Due to the action of the fine grain strengthening and the phase constituent, the wear resistance and microhardness of pure Ti surface were greatly improved.

scholarly journals Laser Cladding of Ni-Co-W Composite Coating on Stainless Steel to Enhance Wear Resistance

2021 ◽  
Author(s):  
Linlin ZHANG ◽  
Dawei ZHANG
Keyword(s):  
Stainless Steel ◽  
Wear Resistance ◽  
Composite Coating ◽  
Laser Cladding ◽  
Composite Coatings ◽  
Eutectic Structure ◽  
Wear Properties ◽  
Fine Grained ◽  
Noticeable Improvement ◽  
Enhance Wear Resistance

Ni-Co-W composite coatings modified by different contents of Co-based alloy powder in the Ni-based alloy with 35 wt.% WC (Ni35WC) were deposited on stainless steel by laser cladding. The influence of compositional and microstructural modification on the wear properties has been comparatively investigated by XRD, SEM, and EDS techniques. It was found that the austenite dendrites in the modified coating adding 50 wt.% Co-based alloy were refined and a lot of Cr23C6 or M23(C, B)6 compounds with fine lamellar feature were formed around austenitic grain boundaries or in the intergranular regions. The contribution of element Co to the modification of Ni35WC coating is that it cannot only promote the formation of more hard compounds to refine austenite grains, but also refine the size of precipitates, and change the phase type of eutectic structure as a result of disappeared Cr boride brittle phases. A noticeable improvement in wear resistance is obtained in the Ni35WC coating with 50 wt.% Co-based alloy, which makes the wear rate decreased by about 53 % and 30% by comparison to that of the substrate and the Ni35WC coating, respectively. It is suggested that the improvement is closely related to the composite coating being strengthened owing to the increase of coating hardness, formation of a fine-grained microstructure caused by Co, and fine hard precipitate phases in the eutectic structure.

scholarly journals Effect of High−Speed Powder Feeding on Microstructure and Tribological Properties of Fe−Based Coatings by Laser Cladding

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1456
Author(s):  
Qiang Wang ◽  
Runling Qian ◽  
Ju Yang ◽  
Wenjuan Niu ◽  
Liucheng Zhou ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Tribological Properties ◽  
Wear Mechanism ◽  
High Speed ◽  
High Efficiency ◽  
Adhesive Wear ◽  
Steel Substrate ◽  
Powder Materials ◽  
Powder Feeding

In order to improve the wear resistance of 27SiMn steel substrate, Fe−based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high−speed powder feeding (HF) process was used to prepare Fe−based alloy coating on 27SiMn steel substrate. The effect of diversified energy composition of powder materials on the microstructure and properties of coatings were systematically studied. X−ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the phase structure and microstructure of Fe−based alloy coatings, and the hardness and tribological properties were measured by the microhardness tester and ball on disc wear tester, respectively. The results show that the microstructure of conventional gravity feeding (GF) coatings was composed of coarse columnar crystals. In comparison, owing to the diversification of energy composition, the microstructure of the high−speed powder feeding (HF) coatings consists of uniform and small grains. The total energy of the HF process was 75.5% of that of the GF process, proving that high−efficiency cladding can be achieved at lower laser energy. The refinement of the microstructure is beneficial to improve the hardness and wear resistance of the coating, and the hardness of the HF coating increased by 9.4% and the wear loss decreased to 80.5%, compared with the GF coating. The wear surface of the HF coating suffered less damage, and the wear mechanism was slightly adhesive wear. In contrast, wear was more serious in the GF coating, and the wear mechanism was transformed into severe adhesive wear.

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