scholarly journals Preparation of WC Reinforced Co-Based Alloy Gradient Coatings on a H13 Mold Steel Substrate by Laser Cladding

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 176
Author(s):  
Chenchen Li ◽  
Xuefeng Yang ◽  
Shouren Wang ◽  
Yanjun Wang ◽  
Jinlong Cao

H13 die steel often fails as a result of physical and chemical effects such as wear, erosion and cyclic stress. Accordingly, the study evaluates Co-based gradient coating on an H13 steel featuring a stress-relieving effect. Scanning electron microscope and X-ray diffraction were used to analyze the microstructure and phase of the coatings. A microhardness tester and friction and wear tester were used to compare the hardness and wear resistance of the coatings and the substrate, and the wear morphology was observed. A pendulum impact test was used to compare the impact resistance of the coatings and the substrate, and the fracture morphology was observed. Finally, a corrosion test was used to compare the corrosion resistance of coatings and substrate. The results show that the Co-based gradient coatings have good combinations with the substrate, the hard phase content gradually increases from the bottom to the top of the coating, and the crystal microstructure generally maintains a distribution trend from coarse to fine. The hardness of the gradient coatings is significantly higher than the substrate, and from the coating surface to the substrate, the hardness decreases slowly. The wear loss of the coatings is much lower than that of the substrate, the main wear mechanism of the substrate is abrasive wear, and the main wear mechanism of the coatings is brittle spalling. While the gradient coatings increase the surface hardness, the brittleness also increases, the impact resistance of the coatings is lower than that of the substrate, the fracture form of the substrate is a ductile fracture, and the fracture form of the coating is a brittle fracture. The gradient coatings effectively improve the corrosion resistance of the substrate surface, and the higher the content of the reinforcing phase, the better the corrosion resistance of the coatings.

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2621
Author(s):  
Aneta Bartkowska

The paper presents the results of a study of the microstructure, chemical composition, microhardness and corrosion resistance of Cr-B coatings produced on Vanadis 6 tool steel. In this study, chromium and boron were added to the steel surface using a laser alloying process. The main purpose of the study was to determine the impact of those chemical elements on surface properties. Chromium and boron as well as their mixtures were prepared in various proportions and then were applied on steel substrate in the form of precoat of 100 µm thickness. Depending on the type of precoat used and laser processing parameters, changes in microstructure and properties were observed. Coatings produced using precoat containing chromium and boron mixture were characterized by high microhardness (900 HV0.05–1300 HV0.005) while maintaining good corrosion resistance. It was also found that too low laser beam power contributed to the formation of cracks and porosity.


2010 ◽  
Vol 150-151 ◽  
pp. 1325-1329
Author(s):  
Jian Fei Liu ◽  
Zhi Wang ◽  
Yin Sen Ding ◽  
Guo Pu Shi

The composites of Fe/Al2O3 gradient coatings on steel substrate were prepared by spraying and sol-gel method, and the microstructure and performances of the composites were analyzed. The results show that the adhesion strength of Fe/Al2O3 gradient coatings with FeAlNi transitional layers reaches 25.3MPa when the sintering temperature is 1220°C, and the surface hardness of coatings is four times higher than that of steel substrate. The coatings are mainly composed of α-Al2O3, AlFeO3 and NiFe2O4. There is no obvious hole or macro-interface, while some organization similar to the branch appears in the coatings. The bonding of Fe/Al2O3 gradient coatings and steel substrate mainly depends on adsorption, diffusion and chemical combination.


2012 ◽  
Vol 57 (3) ◽  
pp. 665-670 ◽  
Author(s):  
N. Radek ◽  
N. Konstanty

The main objective of the present work was to determine the influence of laser treatment on microstructure, microhardness, roughness, bonding strength, corrosion resistance and tribological properties of wear resistant coatings produced on C45 carbon steel by the electro-spark deposition (ESD) process. Consumable WC-Co-Al2O3 electrodes were prepared by the powder metallurgy route and transferred to the substrate surface using the EIL-8A apparatus. The cermet layers were subsequently melted by means of the BLS 720 Nd:YAG laser. The coating characterisation studies showed marked improvements in the bonding between the steel substrate and the cermet coating, and in corrosion resistance at the expense of higher surface roughness and minor drop in the Vickers microhardness.


Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 35 ◽  
Author(s):  
Xiaoxing Yan ◽  
Lin Wang ◽  
Xingyu Qian

An aluminum/waterborne acrylic coating was developed by orthogonal experiments, and the gloss, emissivity, chromatic distortion, hardness, adhesion, impact resistance, and corrosion resistance of the coatings were examined. The results showed that the effect of drying time on the infrared emissivity of coatings was more significant than that of the Al powder concentration and nano-silica slurry. When the drying time was prolonged from 0.5 to 6.0 min, the gloss of the coating decreased slowly and the gloss remained low. The infrared emissivity first decreased and then increased. The infrared emissivity of coatings dried for 2.0 min was better. The L’ value gradually decreased and showed a small change of range. With the increasing of the drying time, the hardness of the coating gradually decreased and was the highest at 0.5–2.0 min. The drying time had no effect on the adhesion level. The impact resistance of the coating was better during the drying period of 1.0–3.0 min. The corrosion resistance of the coating was better at 2.0 min. When the drying time was 2.0 min, the waterborne coating showed the better comprehensive performance. This study provides new prospects in using low infrared emissive coatings for infrared stealth and compatibility with visible light.


2021 ◽  
Vol 27 (3) ◽  
pp. 146-151
Author(s):  
Thanh Van Nguyen ◽  
Van Thanh Doan ◽  
Trung Van Trinh ◽  
Huy Van Vu

AISI 420 stainless steel is widely used in applications where wear and corrosion resistance are required. However, the heat treatment and nitriding process can drastically reduce the corrosion resistance of this stainless steel. This article focuses on investigating the influence of steel substrate and gas nitriding efficiency at two temperatures of 520 oC and 550 oC on some properties of CrN coating. The experiments were carried out to evaluate the surface hardness, microstructure and phase composition of nitrided layers. The coating adhesion and load capacity of the coating were performed according to VDI 3198 standard. Electrochemical testing was performed in a solution of 3.5% NaCl and then using the Tafel method to determine the corrosion current and corrosion potential. The thickness of CrN and CrN/CrN coating was 1.6 μm and 3 μm, respectively. The study showed that the corrosion resistance of coatings fabricated through duplex technology was affected not only by the normal defects but also by the porosity on the nitrided surface. The corrosion resistance of multilayer duplex coating was improved compare with mono-layer duplex coating due to its ability to cover and reduce pores and pitting defects.


2010 ◽  
Vol 654-656 ◽  
pp. 1972-1977
Author(s):  
Yi Wang Bao ◽  
Kun Ming Li ◽  
De Tian Wan ◽  
Xue Qiang Cao

Spherical impact indentation tests with different impact angles (90°, 60°, 45°, and 30°) were carried out to understand the impact resistance and interfacial adhesion of zirconia (ZrO2) ceramic coating on steel and aluminum substrates, respectively. A linear rail with an adjustable impact angle was used to guide the slipping impact head to impact the specimen. It is found that the peak impact force for surface damage decreases but the contact indentation becomes longer with decreasing impact angle. Under almost the same peak impact force, the smaller the impact angle, the higher the impulse. The experimental results indicate that the ZrO2 coating on steel substrate has higher impact resistance than that on the aluminum substrate. The cross bonded test results show that ZrO2 coating on both steel and aluminum substrates exhibit excellent interfacial tensile and shear strength.


Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 597 ◽  
Author(s):  
Yan

A fluorine resin/aluminum infrared coating was prepared with aluminum using black paste as filler and fluorine resin as binder. The effect of the black paste content on the performance of gloss, color difference, infrared emissivity, hardness, adhesion, impact resistance, roughness, optical testing, and corrosion resistance of the fluorine resin/aluminum infrared coating were examined. When the content of black paste was increased from 1.0% to 9.0%, the gloss of the coating surface decreased; the ΔE* value of the coating decreased; the infrared emissivity of the coating surface increased gradually; the hardness of the coating was 6H; the adhesion grade of the coating was 0; the infrared absorption peak increased gradually. When the content of black paste was 0%–3.0%, the impact resistance was more than 50 kg∙cm, and the impact resistance was higher. When the content of black paste was 0%–5.0%, the surface roughness of the coating was relatively low. When the content of black paste was 1.0%, the corrosion resistance of the coating was the best. The results showed that when the content of black paste was 1.0%, the performance of the whole fluorine resin coating was the best. Through the preparation and characterization of fluorine resin infrared low-emissivity coatings, the possibility of applying fluorine resin to infrared low-emissivity anticorrosive coatings was discussed, which laid a foundation for the subsequent engineering application of coatings.


Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3802
Author(s):  
Laura Elena Geambazu ◽  
Cosmin Mihai Cotruţ ◽  
Florin Miculescu ◽  
Ioana Csaki

High-entropy alloys could provide a solution for corrosion resistance due to their impressive properties. Solid-state processing of high purity Co, Cr, Fe, Ni and Mo metallic powders and consolidation resulted in a bulk material that was further machined into electro spark deposition electrodes. After the stainless steel substrate surface preparation, thin successive layers of the high-entropy alloy were deposited and Pull-Off testing was performed on the newly obtained coating, for a better understanding of the adhesion efficiency of this technique. Good adhesion of the coating to the substrate was proved by the test and no cracks or exfoliations were present. Corrosion resistance testing was performed in a liquid solution of 3.5 wt.% NaCl for 6 hours at room temperature and the results obtained validated our hypothesis that CoCrFeNiMo0.85 high-entropy alloys could provide corrosion resistance when coating a stainless steel substrate.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3580
Author(s):  
Pao-Chang Chiang ◽  
Chih-Wei Chen ◽  
Fa-Ta Tsai ◽  
Chung-Kwei Lin ◽  
Chien-Chon Chen

In this paper, we used two mass-produced industrial technologies, namely, thermal spraying and anodization methods, to enhance the surface characteristics of AISI 1045 medium carbon steel for use in special environments or products. The anodic film can effectively improve the surface properties of carbon steel. A sequence of treatments of the carbon steel substrate surface that consist of sandblasting, spraying the aluminum film, annealing, hot rolling, cleaning, grinding, and polishing can increase the quality of the anodized film. This paper proposes an anodization process for the surface of carbon steel to increase the corrosion resistance, hardness, color diversification, and electrical resistance. The resulting surface improves the hardness (from 170 HV to 524 HV), surface roughness (from 1.26 to 0.15 μm), coloring (from metal color to various colors), and corrosion resistance (from rusty to corrosion resistant). The electrochemical corrosion studies showed that the AISI 1045 steel surface with a hard anodized film had a lower corrosion current density of 10−5.9 A/cm2 and a higher impedance of 9000 ohm than those of naked AISI 1045 steel (10−4.2 A/cm2 and 150 ohm) in HCl gas.


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