Chromium Carbide Research Articles

Cr-Diamond/Cu Composites with High Thermal Conductivity Fabricated by Vacuum Hot Pressing.

Chromium-plated diamond/copper composite materials, with Cr layer thicknesses of 150 nm and 200 nm, were synthesized using a vacuum hot-press sintering process. Comparative analysis revealed that the thermal conductivity of the composite material with a Cr layer thickness of 150 nm increased by 266%, while that with a Cr layer thickness of 200 nm increased by 242%, relative to the diamond/copper composite materials without Cr plating. This indicates that the introduction of the Cr layer significantly enhanced the thermal conductivity of the composite material. The thermal properties of the composite material initially increased and subsequently decreased with rising sintering temperature. At a sintering temperature of 1050 °C and a diamond particle size of 210 μm, the thermal conductivity of the chromium-plated diamond/copper composite material reached a maximum value of 593.67 W∙m-1∙K-1. This high thermal conductivity is attributed to the formation of chromium carbide at the interface. Additionally, the surface of the diamond particles in contact with the carbide layer exhibited a continuous serrated morphology due to the interface reaction. This "pinning effect" at the interface strengthened the bonding between the diamond particles and the copper matrix, thereby enhancing the overall thermal conductivity of the composite material.

Microstructural and mechanical properties of chromium carbide thin layers elaborated by conversion treatment process with two methods on 16Mn2 steel

Microstructural and mechanical properties of chromium carbide thin layers elaborated by conversion treatment process with two methods on 16Mn2 steel

Synthesis of chromium carbide powder by vacuum-free electric arc plasma method

Chromium carbide powders were synthesized by vacuum-free electric arc method using pure chromium and carbon powder as starting components. The powders obtained in the experimental series were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), laser diffraction and differential thermal analysis. In the experiments, electrical parameters were recorded, and the thermal field generated in the reaction zone was measured using an infrared camera and tungsten‑rhenium thermocouples. The study results show the feasibility of plasma arc discharge synthesis of chromium carbide compounds Cr3C2 and Cr7C3 within 60 s at current intensity of 200 A. SEM analysis of the resulting powder shows that it consists of acute-angled particles of ∼9 to ∼50 μm in size. An updated design of the discharge circuit employed in the study significantly increases the purity of the final product. Vacuum-free electric arc synthesis of chromium carbide has been studied for the first time.

Microstructure and Mechanical Properties of Laser Direct Energy Deposited Martensitic Stainless Steel 410.

The aim of this work is to study the phase transformations, microstructures, and mechanical properties of martensitic stainless steel (MSS) 410 deposits produced by laser powder-directed energy deposition (LP-DED) additive manufacturing. The LP-DED MSS 410 deposits underwent post-heat treatment, which included austenitizing at 980 °C for 3 h, followed by different tempering treatments at the temperatures of 250, 600, and 750 °C for 5 h, respectively. The analyses of phase transformations and microstructural evolutions of LP-DED MSS 410 were carried out using X-ray diffraction, SEM-EDS, and EBSD. Vickers hardness and tensile strength properties were also measured to analyze the effects of the different tempering heat treatments. It revealed that the as-built MSS 410 has very fine lath martensite, high hardness of about 480 HV1.0, and tensile strength of about 1280 MPa, but elongation was much lower than the post-heat-treated ones. Precipitations of chromium carbide (Cr23C6) were most commonly observed at the grain boundaries and the entire matrix at the tempering temperatures of 600 °C and 750 °C. In general, the tensile strength decreased from 1381 MPa to 688 MPa as tempering temperatures increased to 750 °C from 250 °C. Additionally, as the tempering temperature increased, the chromium carbide and tempered martensite structures became coarser.

A simple and feasible method for preparing chromium carbide coating on graphite through binary NaCl-KCl molten salt

Due to excellent high temperatures resistance and wear resistance, graphite showed great potential apply in refractory materials. However, the porosity defects caused by the layered stacked structure of graphite would lead to easy permeability, which would result in reducing material’s lifetime. Surface coating technology was considered to be an ideal method to solve the problems through a stable coating on the surface of graphite. But existing methods have some disadvantages, such as high-cost and complex processes. In this work, a simple, low-cost and green molten salt method was designed. This method successfully prepared a Cr7C3 coating on the graphite surface. The effect of reaction time and temperatures on the chromium carbide coating was investigated by SEM and EDS. The results showed that the thickness of the coating layer increased gradually with the increase in reaction time or reaction temperature, and finally stabilized at about 8 μm. In addition, the reasons behind the formation of Cr7C3 coatings were discussed in terms of both the molten salt reaction and Gibbs free energy, as well as the effect of the coating structure on adhesion. Based on this method, it could not only effectively address the structure defects of graphite, but also showed simple preparation processes and low cost, which would promote the development of graphite materials in high-temperature resistant materials.

Recognition of Intergranular Corrosion in AISI 304 Stainless Steel by Integrating a Multilayer Perceptron Artificial Neural Network and Metallographic Image Processing

The correct management of operations in thermoelectric plants is based on the continuous evaluation of the structural integrity of its components, among which there are elements made of stainless steel that perform water conduction functions at elevated temperatures. The working conditions generate progressive wear that must be monitored from the perspective of the microstructure of the material. When AISI 304 stainless steel is subjected to a temperature range between 450 and 850 °C, it is susceptible to intergranular corrosion. This phenomenon, known as sensitization, causes the material to lose strength and generates different patterns in its microstructure. This research analyzes three different patterns present in the microstructure of stainless steel, which manifest themselves through the following characteristics: the absence of intergranular corrosion, the presence of intergranular corrosion, and the precipitation of chromium carbides. This article shows the development of a methodology capable of recognizing the corrosion patterns generated in stainless steel with an accuracy of 98%, through the integration of a multilayer perceptron neural network and the following digital image processing methods: phase congruence and a gray-level co-occurrence matrix. In this way, an automatic procedure for the analysis of the intergranular corrosion present in AISI 304 stainless steel using artificial intelligence is proposed.

Prevention of weld decay in TIG-welded AISI 304 steel pipes

Weld decay occurs due to chromium carbide precipitation at grain boundaries in the heat-affected zone (HAZ) during tungsten inert gas (TIG) welding of austenitic stainless steels. This issue is particularly significant concerning the welding of AISI 304 steels, commonly used in the food industry. Although this problem can be overcome with different methods, there are some restrictions. A novel technique for welding AISI 304 steel pipes is introduced to reduce weld decay and improve their mechanical properties. The use of this technique, which includes faster cooling after welding, significantly minimizes the time of precipitation of chromium carbide. Temperature measurements and microstructural analyses monitored precipitation, and the impact of the technique on the mechanical characteristics of AISI 304 steel pipes was assessed through hardness and hoop tensile tests. There was a 6% increase in hardness values observed in the HAZ region, as well as a 16.7% increase in maximum load and a 127.4% increase in elongation. The reduction in chromium carbide precipitation observed in the microstructural analysis was confirmed through the double-loop electropotentiokinetic reactivation test, specifically for assessing intergranular corrosion. With the novel method, there were a 25% increase in corrosion resistance in the HAZ and a 40% increase in the weld zone.

Effect of SS-316L and nickel-based interface powders on joint characteristics of microwave welded SS-316L plates

Microwave energy has been exploited as a rapid and volumetric heating source in various manufacturing applications, such as microwave joining. This study used stainless steel (SS-316L) plates to be microwave-joined at 2.45 GHz. The microwave hybrid heating (MHH) technique was used to prepare joints inside a microwave applicator using nickel-based (EWAC 1004EN) and SS-316L interfacing powders at 900 W. Microstructural and mechanical characterizations of the developed joints were performed to understand the effect of the interface powder on weld quality. Microstructural observations revealed adequate metallurgical bonding between interfacing powders and bulk metal with columnar and dendritic grains (EWAC-based joint) and equiaxed grains (SS-316L-based joint). The phase analysis revealed the presence of intermetallic phases such as iron-nickel, chromium carbide, and chromium iron carbide in EWAC-based joint and iron-nickel, nickel-chromium, and chromium carbide in SS-316L-based joint, which contribute to enhanced joint microhardness compared to base alloys. A larger grain size, more low-angle boundaries, and higher misorientation angles were found in the EWAC-based joint. Furthermore, the average ultimate tensile strength of SS-316L-based joints was 26% higher, with a 6.9% enhanced elongation, than that of EWAC-based joints. The EWAC-based joint exhibited better corrosion resistance than that of SS-316L-based joint.

Effect of graphene and niobium carbide on microstructure and mechanical properties of Ni60 composite coatings prepared by laser cladding

Niobium carbide (NbC) is often used as a reinforcing phase to improve the mechanical properties of composite coatings, but its low thermal conductivity makes the flow of molten pool poor, and the cladding layer is prone to defects such as non-fusion and slag inclusion. Therefore, in this paper, Ni60–NbC composite coatings with different NbC content were prepared by laser cladding technology, and the 10 vol% graphene-20 vol% NbC-70 vol% Ni60 composite coatings were prepared under the optimal NbC component. The effects of the addition of NbC and graphene on the microstructure and microhardness of the coating were systematically discussed. The results show that the microhardness of 20 vol% NbC composite coating is increased from 680.1 HV to 882.9 HV compared with Ni60 coating without NbC.The composite coating with both NbC and graphene has a microhardness of up to 1048HV, which is 18% higher than the composite coating with only 20 vol% NbC. The mechanism is that the addition of graphene promotes the formation of chromium carbide (Cr23C6, Cr7C3) and increases the fluidity of the molten pool, which causes small niobium carbide particles to dissolve and recondense to form large particles. Large niobium carbide particles and chromium carbide jointly inhibit the excessive growth of other grains. This study provides a new idea for laser cladding of nickel-based composite coatings.

Influence of ageing treatment time on microstructural evolution, sensitization and self-healing of Inconel 600

Samples of Inconel 600 were thermally aged at 739 °C from 1 up to 300 h followed by water quenching. The changes in microstructure were characterized and its effect on sensitization was evaluated by subjecting the heat-treated samples to double-loop electrochemical potentiokinetic reactivation (DL-EPR) tests. The evolution of the microstructure was analysed in terms of grain size, carbide formation and chromium diffusion by optical and scanning electron microscopy. The results showed that the formation of chromium carbides is rapid at this temperature, increasing the density of carbides at the grain boundaries in the early stages of the ageing treatment. The formation of Cr7C3 and Cr23C6 along the grain boundaries and within the austenitic matrix modified the corrosion behaviour as seen in the measurements of the degree of sensitization (DOS). A decrement in DOS was seen with ageing time up to 200 h, due to the redistribution of chromium, induced by the equilibrium between chromium at grain boundaries and within the matrix. Electron backscattering diffraction suggested that self-healing of the alloy may be due to the mechanism of near-boundary gradient zones, where the increased number of dislocations leads to precipitation of carbides by promoting diffusion and thereby decreasing the Cr-depleted zones.

Effect of Ce on Inclusions and Precipitates in 10Cr5MoV Steel and the Microscopic Behavior of Solid Solution Ce in Steel

In this article, the effects of Ce (0–120 ppm) on inclusions and precipitates in industrially produced CO2/H2S‐resistant 10Cr5MoVCe special oil well pipe steel and the microscopic behavior of Ce solid solution in steel were systematically studied by scanning electron microscopy, transmission electron microscopy, electrolysis separation of nonaqueous mixed solutions, and first‐principles calculations. After adding Ce to 10Cr5MoV steel the inclusions changed from chain‐like Al2O3 inclusions to polygonal Ce–O–S–Al–Ca complex inclusions and spheroidal Ce2O3, CeAlO3, Ce2O2S, and CeS inclusions. When the total Ce content was 25–120 ppm, the solid solution Ce content was maintained at about 20% of the total Ce content. The Ce had no significant influences on the types of chromium carbide precipitates, and the chromium carbide precipitates of all tested steels were Cr23C7 and Cr7C3. However, with the increase of Ce, the content of Cr23C7 and Cr7C3 precipitates decreased slightly, from 1.27% without Ce to 1.18% when Ce was 120 ppm. The first‐principles calculation results show that there was strong interaction between Fe, Ce, and Cr. Ce enhanced the interaction force between the Fe and Cr atoms, and improved the stability of the system, which facilitated the solid solution of Cr in the Fe–Cr system.

Friction Stir Processing of AA6061 Aluminum Alloy Reinforced with Ceramic Particles for Enhanced Mechanical Properties

This study investigates the effect of incorporating ceramic particles, specifically Chromium Carbide (CrC), Tantalum Carbide (TaC), and Niobium Carbide (NbC), on the mechanical properties of AA6061 aluminum alloy. The investigation uses the Friction Stir Processing (FSP) fabrication technique. The results indicate substantial enhancements in mechanical properties compared to the material without reinforcement. Reinforced composites display elevated longitudinal and shear velocities, which signifies enhanced rigidity and ability to withstand deformation when subjected to different force directions. Using CrC and TaC reinforcements in the AA6061/CrC+TaC composite led to the maximum velocities for both wave types, indicating a notably rigid composite material. Introducing ceramic particles to AA6061 significantly augments Young’s and shear modulus, indicating improved strength and stiffness. AA6061/CrC+TaC showed the most notable enhancement of all the reinforcements, underscoring the potential of using combined reinforcements. Incorporating ceramic particles into AA6061 greatly enhances its microhardness and Vickers hardness. The addition of Tantalum Carbide (TaC) as a reinforcement resulted in the most significant enhancement, indicating a robust interaction with the matrix. Notably, composites with a combination of reinforcements (CrC+TaC and CrC+NbC) displayed even greater hardness, possibly due to synergistic effects.

Effect of Ti and C addition on oxidation resistance of FeCoCrNiMn high entropy alloys prepared by powder metallurgy

Purpose The purpose of this paper is to study the high temperature oxidation behavior of Ti and C-added FeCoCrNiMn high entropy alloys (HEAs). Design/methodology/approach Cyclic oxidation method was used to obtain the oxidation kinetic profile and oxidation rate. The microstructures of the surface and cross section of the samples after oxidation were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Findings The results show that the microstructure of the alloy mainly consisted of FCC (Face-centered Cubic Structure) main phase and carbides (M7C3, M23C6 and TiC). With the increase of Ti and C content, the microhardness, strength and oxidation resistance of the alloy were effectively improved. After oxidation at a constant temperature of 800 °C for 100 h, the preferential oxidation of chromium in the chromium carbide determined the early formation of dense chromium oxide layers compared to the HEAs substrate, resulting in the optimal oxidation resistance of the TC30 alloy. Originality/value More precipitated CrC can preferentially oxidize and rapidly form a dense Cr2O3 layer early in the oxidation, which will slow down the further oxidation of the alloy.

Preparation of Cr-N coatings on 316H stainless steel via pack chromizing and gas nitriding, and their resistance to liquid metal corrosion in early stages

Liquid metal corrosion has become a critical issue in lead-cooled fast reactor when the steel encounters lead–bismuth eutectic (LBE). Although various coatings applied in LBE have garnered interest from many researchers, there are few reports on the compatibility of chrome carbide or chromium nitride coatings in LBE. Thus, Cr carbide and Cr-nitride coatings with thicknesses of 80 μm were prepared on 316H stainless steel (SS) to investigate the corrosion behavior in contact with static liquid LBE at 550 °C for 25, 76, and 207 h. These coatings were synthesized via pack chromizing and subsequent gas nitriding. The results showed that a distinct LBE penetration layer appeared on the surface of the as-received 316H SS after exposure to LBE. Pack-chromized coating and pack-chromized + gas nitride coating did not undergo obvious consumption in LBE in the early stages. Cracks in the pack-chromized coating promoted the preferential diffusion of oxygen and PbBi. The Cr in the pack-chromized + gas nitride coating slightly diffused outward to combine with oxygen to form Cr-oxide scale on the coating surface. These coatings act as a barrier to LBE corrosion, making the surface of the coating impermeable to LBE.

Carbide particle strengthened Cu/graphene composites in-situ fabricated by alloying

Interface structure plays a crucial role in enhancing the electrical conductivity and mechanical properties of copper/graphene composites, thereby influencing their potential applications. In this study, we introduced carbide-forming elements (Cr, Nb, W) and expected to generate nano carbide particles at the interface to improve the interface bonding by in-situ preparation. Among these, the CuCr/graphene composite exhibits the best performance with electrical conductivity of 97 % IACS and hardness of 82 HV. The cold-drawn wire possesses a high tensile strength of 518 MPa. At the Cu/graphene interface, an optimal quantity of nanometer chromium carbide (Cr3C2) particles in situ formed, enhancing the interface bonding and resulting in the composite achieving both high conductivity and high strength.

Heat Treatment, Microstructure, Hardness and Corrosion Resistance of Martensitic Stainless Steel X65Cr13 (1.4037)

Abstract The corrosion resistance of martensitic stainless steels is influenced by the alloy composition and the heat treatment. It is known that the proportion of chromium carbides in the microstructure and the resulting hardness are influenced by the heat treatment (austenitization temperature and duration, cooling rate, deep freezing, tempering temperature). The connection between carbon content, the exact heat treatment parameters and corrosion resistance of martensitic stainless steels with 13 wt.% chromium is only known for lower carbon contents (X20Cr13, X46Cr13). This paper is therefore dedicated to the steel X65Cr13, which is used in particular for razor blades. Materials research results are presented that show the influence of hardening on microstructure, hardness and corrosion resistance. It is shown that the steel X65Cr13 has only limited corrosion resistance due to its high carbon content, which can be attributed to the presence of chromium carbides and local chromium depletion in the microstructure. It is also clear that higher austenitizing temperatures and durations as well as high cooling rates lead to an improvement in corrosion resistance. However, this approach also causes retained austenite, which still has to be converted into martensite by deep freezing after quenching.

The Effect of Niobium Addition on the Operational and Metallurgical Behavior of Fe-Cr-C Hardfacing Deposited by Shielded Metal Arc Welding

Hardfacing is commonly used in parts recovery and in obtaining surfaces with improved properties. Within this field, it is important to analyze the effect of alloying elements on the properties of the deposited layers. One of the critical parameters affecting alloying performances in SMAW is improper arc length. This article examines the effect of the addition of niobium in different quantities (0, 2, 4, 6, and 8% by weight) to the electrode coating in Fe-Cr-C shielded metal arc welding (SMAW), with short and long arc lengths, on the operational process efficiency, dilution, arc energy, microstructure, and microhardness of the deposited layers. A decrease in operational process efficiency and dilution was found with increases in niobium content. On the other hand, it was found that adding niobium leads to a refinement in chromium carbide sizes, directly affecting the hardness of the obtained deposits. There is a direct relationship between the arc energy, with both short and long arc lengths, leading to a tendency to decrease the dilution in the obtained hardfacing.

Superhydrophobicity on AISI 304 stainless steel through surface sensitization process and etching

In this research, the surface sensitization process of austenitic stainless steel (304) was used to create the superhydrophobicity through a facile etching method with a significantly lower etching time. In order to utilize the surface sensitization process for the purpose of forming island-like chromium carbide on surface, oxyacetylene flame heat-treatment was performed at 650 °C for one min. After HF etching at ambient temperature, treatment in nitric acid, and the reduction of surface energy by stearic acid modification, a water contact angle (WCA) of 167°, water sliding angle (WSA) of 3°, and water contact angle hysteresis (WCAH) of 7° have been achieved. The sensitization process makes the sample susceptible to intergranular corrosion and uniform micro- and nano-sized pores entirely cover the surface after boiling in nitric acid. This phenomenon is the main reason for creating the hierarchical microstructure on the surface of stainless steel in a shorter time.

Recent progress in carbide‐based composite materials fabricated by laser additive manufacturing processes

AbstractFabricating and introducing new materials with new features is one of the most important goals for many scientific groups. Today, additive manufacturing (AM) is known as one of the new production methods, which can create an excellent opportunity for achieving this goal. As one of the ongoing production processes, the laser AM (LAM) methods have the proper capacity for producing new advanced materials like carbide, nitride, and boride‐based materials. Hence, this work aims to review carbide‐based materials produced by LAM techniques with the composite viewpoint. These materials can act as a matrix, reinforcement, or tertiary component in advanced composites. With this viewpoint, these composite materials were introduced in eight separate sections, which are tungsten carbide, titanium carbide, silicon carbide, niobium carbide, chrome carbide, vanadium carbide, and boron carbide, as well as high entropy alloy composites.

Intergranular Corrosion Analysis of Austenitic Stainless Steels in Molten Nitrate Salt Using Electrochemical Characterization

This study investigates the influence of molten nitrate salt exposure on the intergranular corrosion (IGC) behavior of three grades of austenitic stainless steel (namely, AISI 304, AISI 304H, and AISI 321H). Two electrochemical techniques, double loop electrochemical potentiokinetic reactivation and potentiodynamic polarization methods, are applied after stainless steel is exposed to 600 °C molten nitrate salt, 60% NaNO3, and 40% KNO3 for varying immersion durations. Corrosion morphology is examined using optical microscopy and scanning electron microscopy images to assess susceptibility to IGC. IGC is prompted by the presence of chromium carbides at grain boundaries, which leads to chromium depletion around these carbides. The findings of the experiments reveal distinct IGC behavior among stainless steel grades. For AISI 304, the degree of sensitization (DOS) increases as exposure time progresses. However, AISI 304H and AISI 321H stainless steel exhibit diminishing DOS after 100 and 10 h of exposure, respectively. This trend is attributed to desensitization or the healing effect when stainless steel is exposed to molten salt for a prolonged time. The depletion and recovery of Cr near grain boundaries are confirmed by the inverse relationship to DOS of pitting potential.