Fe-based Composite Coatings Research Articles

Microstructure Analysis of TiC Reinforced Fe-Based Composite Coating by Plasma Cladding

TiC reinforced Fe-based composite coating with 10% and 20% TiC particle were prepared on the surface of substrate Q235 steel by plasma cladding, respectively. The microstructure and formation mechanism of cladding layer were carefully investigated by SEM, EDS and XRD. The results show that metallurgical combination is achieved between coating and substrate, the microstructure of composite coating is composed of dendrite α-Fe, interdendritic eutectic structure (α-Fe, Cr23C6 and CrB) and added TiC particles, and microstructure refinement with the increase of TiC particles content. TiC particles react with Fe-based alloy and part of TiC particles dissolve into coating. The hardness of composite coating has a relationship with TiC particles content and TiC particles distribution, and hardness increase with the increase of TiC particles content. The maximum value of composite coating hardness is 545 HV0.2 and 719 HV0.2, respectively. The major strengthening mechanism is fine-grain strengthening, solid solution strengthening and dispersion strengthening.

Wear Resistance of Fe-Cr-C-TiFe Fe-Based Composite Coating Prepared by Precursor Carbonization-Composition Process and Plasma Cladding

The sucrose was used as a carbonaceous precursor to fabricate composite alloy powder of Fe-Cr-C-TiFe by the precursor carbonization-composition process using the powder matirial of chromium, iron, tungsten, nickel and ferrotitanium. And the powder of Fe-Cr-C-TiFe was used to form a high-chromium iron-base composite coating on substrate of Q235 steel by plasma cladding process. The microstructure and hardness of the coating were investigated by scanning electron microscope (SEM), energy disperse spectroscopy (EDS), microhardness tester. Wear resistance of the coating was tested on wear tester at room temperature and high temperature 600°C compared with the base material Q235 steel and bearing steel. Results show that the coating consists of TiC, (Cr,Fe)7C3 and austenite and the hardness of the coating is 3.4 times as high as the base body Q235 steel. The wear resistance of the coating at room temperature is 11-15 times as high as the base body Q235 steel. The wear resistance of the coating at high temperature 600°C is 2.45 times as high as Q235 steel and is 1.5 times as high as bearing steel. The composite coating has excellent wear resistance because the reinforce phase TiC and (Cr,Fe) 7C3 in the coating have high hardness and good wear resistance. They can play key roles in process of friction and wear.

Study of WC Particles Dissolved by Plasma Surfacing

Specific coatings are frequently used for increasing the life of mechanical parts undergoing severe corrosive and wearing environment. Plasma surfacing has been used to produce high quality coatings with the rapid development of coating technology. In this paper, the dissolution process of WC particles during the plasma surfacing with Fe-based and tungsten carbides composite coatings on AISI 316L stainless steel was studied .The dissolution process of WC particles is investigated by SEM, EDS and phenomenological analysis. Results show that the dissolution of WC particle during the plasma surfacing process is a successive process consisted of dissolution and reaction diffusion. Moreover, the effects of WC dissolved on micro-hardness of coating have been discussed.

Microstructure and Tribological Behavior of Laser in Situ Synthesized TiC-Reinforced Fe-Based Composite Coatings

Fe-based composite coatings reinforced with TiC particles were prepared by laser surface engineering from precursor of ferrotitanium and graphite. Microstructure of the composite coatings was comprised of dendritic TiC dispersed in a ferrite matrix. In situ dendritic TiC was formed by mechanism of precipitating from the liquid Fe–Ti–C alloy system. Composite coatings showed a substantial increase in microhardness in comparison to that of the substrate. Dry sliding wear tests performed at room temperature revealed that the in situ composite coating possessed a considerably reduced wear volume loss owing to the presence of in situ synthesized TiC. A relatively smooth surface was observed for in situ TiC/Fe composite coating due to its high resistance to ploughing and adhesion, which is caused by the uniformly dispersed TiC reinforcement with high volume fraction.

A Fe-Based Amorphous Composite Coating on Al Plate by Electrothermal Explosion Spraying

A Fe-based amorphous composite coating with different thickness on the Al thin plate is prepared by the electrothermal explosion spraying. Compared with other thermal spraying techniques, the electrothermal explosion spraying method can obtain a very high spraying velocity up to 4000m/s. The coating consists of the amorphous matrix and nanocrystal phases (α-Fe)，no laminar phenomenon is observed. The diffusion occurs between the substrate and the coating, showing a diffusion-metallurgical bond. The average hardness of coatings is 8 times larger than that of the Al substrate. The unique hierarchical microstructure at multiple length scales leads to the superior micro-hardness and wear resistance of the coating. The Fe-based composite coatings on Al thin plate have great potential as the promising lightweight wear-resistance structural materials used in the aero technical industry.

An Experimental Study on the Properties of Fe-Based Amorphous Composite Coatings Prepared by Different Processes

Fe-based amorphous composite coatings were deposited on the surface of ASTM-1020 steel plate by different technologies: arc spraying, laser remelting, TIG remelting (with and without water cooling). The microstructure, phase structure and micro-hardness were characterized by using a combination of SEM, XRD and Vickers hardness tester. It shows that the coating prepared by arc spraying presents typical lamellar structure and poor adherence to the substrate. After the remelting treatment, the coating quality is significantly improved by decreasing structure defects such as cracks and pores; the interface shows the metallurgical bonding. The dendritic crystals could be obtained within all the remelted coatings with different appearances. The microstructures of TIG remelted coatings show much more regular and have obvious orientation, which cannot be seen in laser remelted coating. However, the average grain size of the laser remelted coating is much smaller than that of TIG remelted coatings. The micro-hardness values of all of the deposited coatings are much higher than that of the substrate, and the coating prepared by laser remelting shows the highest hardness.

Microstructure and Wear Resistance of Fe-Based Multi-Layers Amorphous Composite Coatings by Tungsten Inert Gas Cladding

Microstructure and Wear Resistance of Fe-Based Multi-Layers Amorphous Composite Coatings by Tungsten Inert Gas Cladding

A Hard and Thick Fe-Based Amorphous Composite Coating

A thick Fe-based amorphous and nanocrystalline composite coating was prepared by in-situ tungsten inert gas (TIG) cladding method. The results show that the cladding coating mainly consists of amorphous phase and nanocrystalline grains. The microstructure study shows that the Fe-based composite coatings have unique microstructure including nano-sized grains surrounded by nano-scale amorphous shell layer (encapsulated structure) and the homogeneously distributed dendrites/cellular crystals. The unique microstructure gives rise to the superior micro-hardness and wear resistance of the coating. The Fe-based coatings have great potential as promising wear-resistance structural materials used in electric power and cement industry.

Fe-Cr-C-TiC High-Chromium Fe-Based Ceramic Composite Coating Prepared by PTA Weld-Surfacing Process

In situ synthesized Fe-Cr-C-TiC high-chromium Fe-based ceramic composite coating was fabricated on substrate of Q235 steel by plasma transferred arc (PTA) weld-surfacing process using the mixture of ferrotitanium, ferrochromium, ferroboron and ferrosilicium powders. The microstructure and wear properties of the composite coating were investigated by XRD, SEM, EDS, microhardness tester and wear tester. Results show that the coating consists of TiC, (Cr,Fe)7C3 and austenite. The coating is metallurgically bonded to the Q235 steel substrate. TiC particles formed by PTA weld-surfacing process present cubic, dendrite and flower-like shape. The wear resistance of the composite coating is approximately 11 times higher than that of the base body Q235. As the load increases, the wear mass loses slowly, which demonstrates the composite coating has excellent load character.

Effect on Microstructure and Hardness of Plunger Piston of Fe-Based Composite Coating by Laser Cladding

The laser cladding of Fe power technology was used to repair worn plunger piston surface. The microstructure of cladding layer, binder course and the matrix were observed by OM and SEM. Besides, the micro-hardness of different zones was measured through micro-hardness testing. The results show that the matrix metal microstructure of plunger piston is made of ferrite and austenite. By laser cladding Fe-based power on base metal, the cladding layer grain is fine and uniform, grain growth has obvious direction and finally become dendrites oriented, the microstructure of cladding layer is both second-phase hard particles and Fe-based solutes. The combination between matrix and cladding layer is smooth, belong to metallurgy bonding. The hardness of cladding layer is higher than that of other parts in three parts, the max value of micro-hardness is about 1250HV, it can agree with wear resistance need of plunge piston surface.

Thermodynamics of Modifying Effect and Experiment Research of Rare Earth in Plasma Jet Surface Metallurgy

The Fe-based composite coatings with RE oxides were prepared on low-carbon steel substrate by use of the plasma jet surface metallurgy, and the effect of RE on microstructure of coating was investigated. The result shows that the microstructure and properties with a proper amount of RE oxides are better than these of the coatings without RE oxides. In addition, the modifying effect of RE oxide on inclusions in metallurgical coating was studied by means of thermodynamics. The thermodynamics analysis shows that RE oxide (Ce2O3) can be reduced to RE by carbon, then the RE element can react with oxygen and sulfur to form the RE oxide-sulfide in metallurgical pool. As a result, the coating is purified and the solidification crack of coating can be restrained by deoxidization and desulphurization.

Microstructure and Properties of Fe-Based Composite Coating by Plasma Jet Surface Metallurgy

The Fe-based composite coatings were formed by plasma jet surface metallurgy using Fe, C, W, Cr and Al alloy powders on the low carbon steel. The morphology, microstructure, interface structure and the distribution of the in situ particles in the coatings were observed with optical microscope, scanning electron microscope and x-ray diffraction analysis. The results show that metallurgical bonding is obtained between coating and substrate, and the microstructure of coatings is mainly composed of γ-Fe, (Fe,Cr,W,Nb)7C3 and AlFe particles which are synthesized in stiu, are dispersivly distributed in the coatings. The micro-hardness gradually increased from bottom to the top of the coating, the maximum is 986 Hv0.1, about 4 times larger than that of the steel substrate.

Fabrication of Fe-Based Amorphous Composite Coatings by Electrothermal Explosion Spraying on Aluminum Substrate

In order to improve the surface properties of the aluminum alloy, an amorphous composite coating was prepared on the surface of the aluminum alloy substrate by electrothermal explosion spraying with fully amorphous Fe-Si-B ribbons. The microstructure, phase structure and micro-hardness of the coating were characterized by SEM, XRD and Vickers hardness tester. The results show that the composite coating is composed of amorphous phase and nanocrystal phase. The coating has dense structure and low porosity. It has not been seen rough laminar microstructure that is frequently obtained by other thermal spray techniques. The amorphous composite coatings with different thickness present higher hardness and show good mechanical properties.

Comparison Study of the Fe-Based Composite Coating Prepared by Different Processes

Comparison Study of the Fe-Based Composite Coating Prepared by Different Processes

Fabrication In Situ TiB2–TiC–Al2O3 Multiple Ceramic Particles Reinforced Fe-Based Composite Coatings by Gas Tungsten Arc Welding

A Fe-based composite coating reinforced by multiple TiB2–TiC–Al2O3 ceramic particles was developed by gas tungsten arc welding (GTAW) melting process. Mixture of aluminum (Al), boron carbide (B4C), and titanium dioxide (TiO2) powders was used as precursors, and as a consequence TiB2–TiC–Al2O3 multiple ceramic particles were in situ synthesized during GTAW melting process. Microstructural investigations showed that TiB2 particles exhibit a blocky morphology, TiC particles are of flower-like shape, and the Al2O3 particles exist as small black dots and located in the core of reinforced particles. The hardness and wear resistance of the coatings increased drastically in comparison with that of the substrate.

Microstructure and Wear Properties of Laser Clad (Ti,Mo)C Multiple Carbide Reinforced Fe-Based Composite Coating

(Ti,Mo)C multiple carbide reinforced Fe-based composite coating was produced by laser melting a precursor mixture graphite, ferrotitanium (Fe–Ti), and ferromolybdenum (Fe–Mo) powders. The results showed that flowerlike and cubic type (Ti,Mo)C multiple carbides were formed during laser cladding process. The selective area diffraction pattern analysis indicated that (Ti,Mo)C crystallizes with cubic structure, which indicates that (Ti,Mo)C carbides were multiple carbides with Mo dissolved in the TiC structure. The formation of (Ti,Mo)C particles was achieved via a nucleation-growth mechanism during the laser cladding process. Increasing the amount of Fe–Mo in the reactants led to a decrease of carbide size and an increase of volume fraction of carbides. The coating possessed good cracking resistance when the amount of Fe–Mo was controlled within a range of 15 wt %. The Fe-based surface coating reinforced by (Ti,Mo)C multiple carbides gave an excellent wear resistance.

Development and characterization of (Ti, Mo)C carbides reinforced Fe-based surface composite coating produced by laser cladding

In this study, in situ multiple carbides reinforced Fe-based surface composite coatings were fabricated successfully by laser cladding a precursor mixture of graphite, ferrotitanium (Fe–Ti) and ferromolybdenum (Fe–Mo) powders. The results showed that (Ti, Mo)C particles with flower-like and cuboidal shapes were in situ formed during the solidification and most shapes of (Ti, Mo)C particles were diversiform according to different contents of Fe–Mo powder in the Fe–Ti–Mo–C system. The growth morphology of the reinforcing (Ti, Mo)C carbide has typically faceted features, indicating that the lateral growth mechanism is still predominant growth mode under rapid solidification conditions. Increasing the amount of Fe–Mo in the reactants led to a decrease of carbide size and an increase of volume fraction of carbides. The coatings had good cracking resistance when the amounts of Fe–Mo were controlled within a range of 15 wt%.

Fe-Based Micro- and Nanocomposite Coatings Produced by Amorphous Alloy Crystallization Based on Electrospark Deposition

The aim of this paper is to explore the possibility of a novel surface technique for Fe-based amorphous and micro-nano composite coatings. A kind of iron based amorphous and micro/nano-crystalline alloy powder which contains Fe, Ni, Cr, W, Mo, B, Si, C etc. was first prepared by mechanical alloying method. Iron based amorphous alloy coatings were then deposited on nodular cast iron substrate by electro-spark deposition using electrode materials with the ball-milling iron based alloy and SiC mixed powders. Annealing crystallization treatment of the Fe-based amorphous alloy coatings was conducted at last. The microstructure and surface morphology of the coating were analyzed by optical microscopy (OM) and scanning electron microscopy (SEM), the amorphous and crystal configuration were confirmed with an X-ray diffractometer (XRD), the microhardness was measured with a micro-sclerometer. The experimental results show that the Fe-based composite coatings are composed of Fe-based amorphous alloy matrix and dispersion strengthened micro- and nanocrystalline particles. The coatings of about 60 m in thickness are uniform, dense and metallurgically bonded to the substrate with high microhardness of about 880 (HV100, 15 S), implying a much improved wear resistance on surface of cast iron.

激光感应复合快速熔覆Fe基WC涂层的显微组织特征

激光感应复合快速熔覆Fe基WC涂层的显微组织特征

Microstructure and properties of Fe-based coatings on cutting pick surface formed by plasma jet surface metallurgy

The Fe-based composite coatings were produced on the attrition spot of cutting pick by plasma jet surface metallurgy, and metallurgical bonding was obtained between coating and substrate. The results show that the microstructure, microhardness, wear resistance and erode resistance of the coating are all evaluated. The coating has apparent characteristics of rapid and layered crystallization from planar crystal-cell/dendritic transition zone on the interface, to equiaxed crystal on the midst, to spike crystal on the surface. The microhardness gradually increases from the bottom to the top of the coating. The composite coating has better wear resistance and erode resistance compared to steel substrate.