Carbide Content Research Articles

Tailored ductility and strength for enhanced impact toughness of laser powder fusion built Alloy 718

Impact toughness of Alloy 718 built via laser powder bed fusion (LPBF) in as-built and thermally post-treated conditions were investigated. The effect of various stages in the thermal post-treatment, including stress relief, hot isostatic pressing, solution treatment, and aging on the microstructure, texture, ductility, hardness, and impact toughness were studied. The greatest impact toughness was found in the as-built Alloy 718 material, associated with the high ductility of the material. The ductility results were also inversely related to the hardness of the investigated materials. Where the material with the highest ductility had the lowest hardness etc. Anisotropy in the impact toughness behavior was present in the as-built and post-heat treated specimens, which was explained by the presence of texture in all of the investigated material. With the applied heat treatments, recrystallization occurred and the preferential crystal orientations were randomized, decreasing the texture. The thermal post-treating conditions rendered different types of microstructures, with various grain sizes. The carbide content remained the same for the three investigated thermal post-treating conditions.

Effect of the content of silane-functionalized boron carbide on the mechanical and wear performance of B4C reinforced epoxy composites

This article presents the mechanical, physical, and tribological properties of the boron carbide (B4C) reinforced epoxy matrix composites (BEMCs). The BEMC samples were prepared with various B4C concentration of 0%, 1%, 2%, 3%, and 5%. B4C particles were treated with a silane coupling agent to ensure efficient adhesion with epoxy. The influence of a range of parameters (particle loading, sliding speed, sliding distance, and normal load) on the wear and friction behavior of BEMCs were evaluated by conducting wear tests under dry sliding conditions on a pin-on-disc wear test set-up. The addition of B4C to the epoxy polymer improved the wear resistance of the composites. Maximum wear resistance and coefficient of friction were observed for the composite with the highest percentage of B4C (5%). The specific wear rate was reduced on increasing load and sliding distance and increased with the sliding velocity. Mechanical properties including compression strength, flexural strength, and impact energy, along with physical properties such as density and hardness, were also evaluated. B4C particles improved the hardness, density, flexural and compression strength, and impact resistance of the composites. Scanning electron microscope (SEM) analysis of the worn-out surfaces and flexural fractured surfaces was carried out to predict the possible wear and fracture mechanisms. Micro-ploughing, abrasion, and adhesion were the wear mechanisms in BEMCs. Under the flexural loads, particulate de-bonding, pull-out, and brittle fracture of the matrix were the governing failure mechanisms.

Synthesis of boron carbide from its elements up to 13 GPa

The synthesis of boron carbide from its elements (boron and carbon) has been studied under pressures up to 13 GPa and optimum parameters have been determined by varying the (P, T, reactants) conditions. Stoichiometric mixtures of amorphous boron and amorphous carbon have been subjected to a range of temperatures from 1673 K to 2273 K at the pressure values of 2 GPa and 5 GPa. The formation temperatures have been compared to those obtained from mixtures of β rhombohedral boron and graphite, and β rhombohedral boron and amorphous carbon at 2 GPa and 5 GPa. The formation temperature is thus shown to be affected by the pressure and the choice of the reactants. The carbon concentration of boron carbide is also shown to be affected by the pressure at which it is synthesised from elements, and we propose pressure as a means to control the carbon content. Temperature cycling has also been shown to reduce the formation temperature of boron carbide at 13 GPa. The formation of α rhombohedral boron as an intermediate phase is seen at 5 GPa before the formation of boron carbide.

Optimization of tribo-mechanical properties of boron carbide reinforced magnesium metal matrix composite

In this study, magnesium–boron carbide composites are developed through the powder metallurgy technique and investigated for their tribological properties using a pin-on-disc tribometer. The process parameters such as load, sliding distance, sliding velocity, and concentration (wt%) of boron carbide are optimized using Taguchi's L16 array. A lower wear rate of magnesium–boron carbide composite is obtained at optimized process parameters. Further, the analysis of variance result shows that the most dominating factor that affects the wear loss is load followed by concentration of boron carbide reinforcement. Moreover, the optimum parameters for the low wear rate of magnesium–boron carbide composites are obtained as 5 N, 6 wt% of boron carbide, 1200 m, and 3 m/s through signal-to-noise ratio analysis. Further, the mechanical properties of magnesium–boron carbide composites such as hardness and compressive strength are also analyzed. The result shows that the hardness and compressive strength of magnesium–boron carbide composites are improved with the inclusion of boron carbide reinforcement.

Processing, microstructure and mechanical properties of Ni1.5CoFeCu0.8Al0.2V0.5 high entropy alloy matrix composites reinforced by in-situ synthesized vanadium carbides

Three in-situ synthesized vanadium carbides (in the volume fraction of 5%, 10% and 15%, respectively) reinforced Ni1·5CoFeCu0·8Al0·2V0.5 high entropy alloy (HEA) matrix composites were prepared by adding V and C in equal molar ratio using mechanical alloying and spark plasma sintering techniques. The formation and evolution of vanadium carbide reinforcements as well as their influences on the microstructure and mechanical properties of HEA matrix composite were investigated intensively. The results show that after milling of 70 h part of V and C from raw materials reacted incompletely through the mechanism of solid-state diffusion at the interface, resulting in the generation of V2C and [VC] in the composite powders. Subsequently, owing to the enhanced atomic diffusion during sintering V2C in the intermediate state was further carbonized into [VC] and partial [VC] was transformed to ordered V8C7 in the consolidated composites. The addition of 5 vol% and 10 vol% vanadium carbides resulted in the significant refinement of grains in the HEA matrix due to the grain boundary pinning effect induced by in-situ generated fine reinforcements. However, grains of the composite containing 15 vol% vanadium carbides are coarser than those of the base HEA due to the serious agglomeration of in-situ synthesized reinforcements. With the increase of vanadium carbides content, mechanical properties of the HEA matrix composite do not change monotonously. The composite reinforced by 10 vol% vanadium carbides performs best among the three and its yield strengths at room temperature, 500 °C, 600 °C and 700 °C are about 1.2, 1.4, 2 and 2.5 times, respectively, than those of the base HEA. The improvement in mechanical properties of composite are attributed to grain boundary strengthening and dispersion strengthening caused by in-situ synthesized vanadium carbide nanoparticles.

Comprehensive analysis of the coated component from a FORD engine

The article is devoted to a comprehensive analysis of the coating of a component from the Ford Fo-cus 1.0 l EcoBoost engine. It is one of a pair of materially identical aluminum gears connected by a drive pulley and a drive. Aluminum gear components are surface treated with a mixture of metal powders using PVD technology, where the goal of the coating is to increase the hardness, abrasion resistance and heat of the base material. The chemical composition of the basic material of the gea-red aluminum drive wheel of the FORD engine proves that it is a component made by thermofor-ming and corresponds to the alloy EN AW 6061 (AlMg1SiCu) according to the standard ČSN EN 573 1-3. The microstructure of the base material component exhibits fine intermetallic phases evenly dis-tributed throughout the cross-section of the base base material, without the occurrence of larger inc-lusions and/or porosity. The cross-sectional microstructure in the area of the coating demonstrates that the component has a continuous uniform surface layer of the coating formed without a defect and does not have a diffuse bond with the base material. The measurement of the coating thickness of the component shows a continuous surface layer formed by powder metallography, which ranges from 70.1 µm to 143.9 µm. The surface EDS of the surface proves that it consists of deposited tungsten carbides produced by powder metallography and the bonding material is cobalt. Area EDS analysis of the surface coating identified morphologically two distinct areas of dark and light, where tungsten carbides and cobalt are based, and only the tungsten carbide and cobalt carbide contents change. The oxygen and carbon content also changes in the dark and light areas.

Spark plasma processing of semi-conductive titanium carbide dispersed alumina composites

ABSTRACT The spark plasma sintering behavior of the alumina ceramic composite that is modified by the spatial distribution of electrically semi-conductive sub-micron scale titanium carbide particles was investigated. Titanium Carbide was reinforced to the alumina composites in different weight percent concentrations of 20, 25, 30, and 35. The influence of titanium carbide particle distribution on the thermal profile, micro-hardness, and wear resistance of alumina ceramic composites was studied. Homogenous spatial distribution of sub-micron scale semi-conductive titanium carbide particles in the composite were noticed through scanning electron microscopy, excluding the 35 weight percent sintered sample. In the spark plasma sintering processed samples, X-ray diffraction results revealed strong α-alumina and titanium carbide peaks. The obtained experimental results show that a higher titanium carbide concentration causes an earlier onset of shrinkage temperature, which positively impacts densification. The addition of titanium carbide particles accelerates the sintering kinetics and improves the properties. Among all composites, the sample with 30 weight percent has the highest relative density of 98.80% and hardness of 20.56 GPa. Besides, the highly densified sample of 30 weight percent has superior wear resistance to all other composites, and can be used for high-temperature sliding applications.

Solid-state phase transformation of ductile cast iron during electroslag remelting cladding

ABSTRACT A bimetallic composite roll with the cladding layer of high-speed steel (HSS) and the roll core of ductile cast iron (DCI) was manufactured by the electroslag remelting cladding (ESRC) technology, and the changes in the graphite morphology, matrix structure, and mechanical properties of the DCI core before and after the ESRC process were compared. The DCI core was first heated to a very high temperature and then cooled down to room temperature during ESRC which led to a deteriorative graphite morphology with a low spheroidisation rate, a large size, and a nonuniform distribution and also caused a solid-state phase transformation of the matrix structure from lamellar pearlite + few carbides to bainite + large amounts of carbides. Based on the changes of graphite sphericity, matrix structure, carbides content, the tensile strength and impact toughness of DCI before and after the ESRC process changed from 458 MPa, 3.02 J/cm2 to 417 MPa, 5.74 J/cm2, respectively.

Optimization of Mechanical Properties of Cr3C2-Ni20Cr/Graphite Cold Sprayed Coatings.

This study analyzed the mechanical properties of cold-sprayed Cr3C2-25(Ni20Cr) blended with Ni-graphite as a solid lubricant deposited on 7075 aluminum alloy substrate. To optimize the coating properties, different sets of parameters (graphite content in feedstock, process gas composition, spraying distance, and traverse gun speed) were tested in the frame of the Taguchi experiment. The cold-sprayed coatings were evaluated for their chromium carbide and graphite content, hardness, and coefficient of friction. Analysis of the microstructure of the deposited coatings revealed that graphite as a soft and brittle component fills all voids in the coating and its quantity depends on its content in the feedstock. The experimental results show that the composition of the process gas has the greatest impact on the Cr3C2 content in the coating and the proportion of graphite in the sprayed blend directly affects its hardness. In the case of the coefficient of friction, the most significant parameters were the graphite content in the sprayed blend, the spraying distance, and process gas composition. The conducted verification experiment with the optimum parameter values allowed a coating with the highest hardness and the lowest coefficient of friction to be obtained.

Effect of WC content on microstructure, hardness, and wear properties of plasma cladded Fe–Cr–C–WC coating

The Q235 sample was coated with ball-milled Fe–Cr–C–WC powder using plasma cladding technology, and the influence of tungsten carbide (WC) content on the surface microstructure, hardness, and wear properties of the coated steel was evaluated. The single factor test of optimal WC content was carried out on DML-02BD plasma cladding machine, and the material after cladding was analyzed. The microstructure distribution, elemental composition and phase composition of the coating were observed by MIRA3-XMH scanning electron microscopy. The microhardness of cladding layer can indirectly reflect the properties of cladding layer to a certain extent, which is measured by the Vickers microhardness tester. The wear quality, friction coefficient and wear mark morphology can directly reflect the wear resistance of the test blocks. These are observed by the ring block friction and wear tester and the ultra depth of field microscope, respectively. With an increasing WC content, the microhardness of the cladding layer shows an upward trend. The main hard phases of the cladding layer after adding WC are (Cr, Fe)7C3, (Fe, Ni)23C7, and the other phases are γ-Fe, Fe3W3C, WCandFe2W. After 6 h friction and wear test, the cladding layer with 30%WC showed the best wear resistance. The total wear amount, wear volume, wear rate and friction coefficient were 0.01 g, 4.22 mm3, 2.344 × 10–4 mm3/(N·m), and 0.35, which were 1/10, 1/5, 1/5, and 7/10 of those without WC cladding layer, respectively. It can be concluded that different WC contents affect the surface microstructure and properties of Fe–Cr–C alloy coating treated by plasma cladding technology. At a WC content of 30%, the microstructure and properties of the cladding layer reach the best.

Ice-melting performance assessment of cement composites using silicon carbide as fine aggregate

This study focused on the assessment of the ice-melting performance of cement composites using silicon carbide as fine aggregate. To assess the ice-melting performance, two mechanical and three thermal properties were measured and the results were discussed. After measuring the mechanical and thermal properties, the ice-melting test was conducted to confirm the ice-melting performance and the mechanical variation was confirmed through a splitting tensile test. The specimen that used 30% of silicon carbide as fine aggregate showed the highest compressive strength of 68.24 MPa at the 28 days of curing age and the specimens that used 100% of silicon carbide as fine aggregate were the lowest compressive strength of 38.93 MPa at the 28 days of curing age. However, the compressive strength that the case of used 100% of silicon carbide was in the acceptable range. The flexural strength increased with silicon carbide contents of up to 70%. The thermal properties including the thermal conductivity, diffusivity, and specific heat capacity showed nearly the same behaviors. These properties increased with the increase of silicon carbide content. The reason for this phenomenon was related to the volumetric occupancy of silicon carbide in the cement composite. The ice-melting test showed the decreasing of melting time with the increase of the silicon carbide content. Comprehensively, it was demonstrated that the ice-melting performance enhanced for the same reason as the thermal properties and, silicon carbide could be used as fine aggregate for improving the thermal properties.

Forecast of mechanical properties of metal products

Introduction. The mechanical properties of the metal depend primarily on their chemical composition and structure. The structure of metal materials is formed under the influence of different temperature modes of manufacture and cooling. Models for predicting the mechanical properties of steels and cast irons are based on the influence of chemical composition and structure. The paper considers an approach that allows to evaluate the mechanical properties of rolling (C) cast iron rolls with a pearlitic (P) matrix depending on the complex influence of the elements of their chemical composition. Materials and methods. The working area of СПХН roll cast iron samples from the surface up to 50 mm doped with chromium (X) and nickel (H) was investigated. The carbide content varied from 10 to 15 %; and lamellar graphite did not exceed 2 %. The results of the experiment. In the work for modeling the mechanical characteristics of cast iron rolls used the method of planning experiments. The choice of this technique is due to the multi-parameter technology of production of solid metal casting. The application of this technique allowed to obtain models for predicting the mechanical characteristics of roll cast iron SPHN depending on the influence of the elements of the chemical composition of the rolls (C, Si, Mn, P, S, Cr, Ni). The error in predicting the tensile strength sВ, bending strength sзгин bending and hardness according to the Shore HSD method did not exceed 5,89 %. When checking the models for convergence of results by Fisher's criterion at a critical value of Fcrit = 2,400 for sВ, this coefficient was 1,249; for sзгин fold was 1,289 and for HSD - 1,012. To analyze the effect of carbon on mechanical characteristics, two-dimensional dependence plots are constructed. Conclusions. Within the operating values of the parameters of the chemical composition of cast iron rolling mills СПХН-45 in accordance with existing regulations, a forecast of their mechanical characteristics within the allowable limits of error of experimental data. The results of the work allow to obtain mathematical models in the process of production of rolls of the СПХН brand to quickly establish their chemical composition within the standard technology in accordance with the customer's requirements for these mechanical characteristics. In addition, the obtained models can predict these characteristics of the manufactured rolls with minimal material and time costs.
 Keywords: rolling mills; elements of chemical composition; mechanical characteristics; multiparameter technology

The Effect of Laser Scanning Speed on Microstructure and Performance of Cr3C2-NiCr Cermet Fabricated by in-situ Laser Cladding

To explore the effect of laser scanning speed on the microstructure and performance of Cr3C2-NiCr cermet layers fabricated by in-situ laser cladding, Cr3C2-NiCr cermet layers were laser cladded from Ni/Cr/Graphite (25:65:10 wt.%) elemental powder mixtures. The microstructures of the laser cladded cermet layers and the formation mechanism were investigated. In addition, the effect of laser scanning speed on the microstructure, friction and corrosion performance of the Cr3C2-NiCr cermet layers was studied. The results indicated that the in-situ laser cladded Cr3C2-NiCr cermet layers were composed of NiCr binder and Cr3C2. The laser scanning speed had a significant influence on the carbide content, composition and size. Furthermore, it affected the in-situ laser cladded cermet layer’s hardness and wear resistance. The corrosion resistance of the in-situ laser cladded cermet layer was superior to that of laser cladded nickel-based alloy and was improved with decreasing laser scanning speed.

Finding the optimum concentration of silicon carbide and graphite particles on the tensile strength, hardness and wear properties of aluminium matrix composites by RSM approach

The present investigation aims to determine the optimum concentration of SiC and graphite reinforcements in AA7075 matrix based hybrid composites to obtain better tensile strength, hardness, coefficient of friction and wear rate using RSM. Reinforcement particles of SiC varied from 5% to 15% whereas graphite particles varied from 3% to 7% in the AA7075 matrix. A central composite design of RSM was adopted to develop the numerical model, and the statistical data were derived using analysis variances to evaluate adequacy of the model. Meanwhile, the conformity test has been conducted to validate the developed numerical model. Following this, the output responses of the optimized conditions were taken into account for the characterization of microstructure, fractured surface, and worn surface characters using optical microscope, and scanning electron microscope. The effect of SiC and graphite particles on the tensile strength, hardness, and wear properties and its result were reported in detail along with comparison of previous researchers.

The Effect of Adding SiC on Some of the Mechanical Properties of the Cu-Al2O3 System Using Powder Metallurgy

Powder metallurgy is one of the simple ways employed to produce alloys that are used in many technological applications. In the recent work, different contents (0, 5, 10, 15 and 20%) of silicon carbide (≥ 63μm) were used as a reinforcement material on matrix ((90, 85, 80, 75 and 70) % Cu-10% Nano-Al2O3). The mixture was milled by a locally made mill for three consecutive times (2, 4 and 6) hours. After that, a compressor with the highest compaction capacity (20 tons) was used to compact the mixture. The mixture was compacted in a steel die through applying pressure of 5 tons for one minute. After sintering samples at 900°C for two hours, mechanical tests including Vickers hardness, diametric compressive strength and wear were applied as a function of the grinding time. The results showed that the best hardness of (119.4 Hv) is reached for the grinding time of six hours and the reinforcement of (20% SiC), while the highest compressive strength was obtained for same time of grinding with a reinforcement of (53.3 Mpa). Concerning the rate of wear, its value decreased to the lowest value at the same conditions above (1.10368*10-7 g/cm). Accordingly, the best characteristic parameters of the results appeared at 900°C, the grinding time of six hours, and reinforcement content of 20%.

Sintered Fe-Mo-Mn-Si-C alloys

Sintered Fe-Mo-Mn-Si-C alloys were produced by alloying silicon and carbon elements to pre-alloyed Fe-0.5Mo-0.15Mn powder via sintering of mixtures of pre-alloyed powder and varied silicon carbide amounts (0.5-4.0 wt.% with 0.5 increment). The sintered alloys were cooled in a sintering furnace. Microstructures and mechanical properties of the sintered alloys were altered depending on added silicon carbide content. With up to 2.0 wt.% silicon carbide additions, the sintered alloys exhibited polygonal ferrite plus eutectoid decomposition products, showing non-cooperative ferrite and carbide growth mode. With silicon carbide contents of ≥ 2.5 wt.%, the sintered alloys exhibited microstructural feature similar to that of a ductile iron, i.e., a common feature consisted of a black particle enveloped with ferrite and pearlite. Tensile strengths of the sintered alloys increased but elongation values decreased with increasing added silicon carbide content. The sintered alloys produced by 3.5 and 4.0 wt.% silicon carbide showed high strengths and considerably good elongation values.

HVDC 케이블 접속재용 실리콘고무/나노 실리콘카바이드 콤포지트의 전기적 특성

In order to develop HVDC cable accessory, space charge exists at the interface between XLPE and EPDM composite or at the interface between XLPE and SiR. The larger the difference in ratio between the dielectric constant and the electrical conductivity of the two insulators, the greater the amount of space charge appears at the interface. The more and more space charges are stored at the interface, the higher the electric field distortion occurs. Therefore, in developing HVDC cable connection materials, Silicone rubber/nano silicon carbide (SiC) contents composites related to insulation and electrical conduction were manufactured. Nano SiC, a semiconducting inorganic material, has been modified to reinforce the interface of the composite mixed with silicon rubber.In addition, in order to study electrical ±HVDC dielectric breakdown characteristics and dielectric characteristics, modified ano SiC was filled with 0, 1, 3, 5, 7, 9wt%, dispersed, and nanocomposite was developed.

Triboinformatic modeling of dry friction and wear of aluminum base alloys using machine learning algorithms

Data-driven methods including machine learning (ML) algorithms can yield a better understanding of how tribological and material properties correlate. Correlations of friction and wear of aluminum (Al) base alloys with their material properties (hardness, yield strength, tensile strength, ductility, silicon carbide content), processing procedure, heat treatment, and tribological test variables (sliding speed, sliding distance, and normal load) studied using traditional and data-driven approaches. Five different ML algorithms, K Nearest Neighbor (KNN), Support Vector Machine (SVM), Artificial Neural Network (ANN), Random Forest (RF), and Gradient Boosting Machine (GBM) applied to experimental tribological data to predict the coefficients of friction (COF) and wear rates. Through performance analysis, we demonstrated that the ML models can satisfactorily predict friction and wear of Al alloys from material and tribological test variables data. Comparative analysis of model performance illustrated that RF outperformed other ML models in wear rate prediction, while KNN exhibited the best performance in COF prediction. Feature importance analysis further revealed that normal load, hardness, and sliding speed have the maximum influence in predicting the wear rate of the alloys. The variation in hardness of the alloys and sliding distance influenced the COF prediction the most.

Triboinformatics Approach for Friction and Wear Prediction of Al-Graphite Composites Using Machine Learning Methods

Abstract Data-driven analysis and machine learning (ML) algorithms can offer novel insights into tribological phenomena by establishing correlations between material and tribological properties. We developed ML algorithms using tribological data available in the literature for predicting the coefficient of friction (COF) and wear-rate of self-lubricating aluminum graphite (Al/Gr) composites. We collected data on effects of material variables (graphite content, hardness, ductility, yield strength, silicon carbide content, and tensile strength), processing procedure, heat treatment and tribological test variables (normal load, sliding speed, and sliding distance) on tribological properties and established two-parameter relationships. These data are analyzed using several ML algorithms: artificial neural network (ANN), K nearest neighbor (KNN), support vector machine (SVM), gradient boosting machine (GBM), and random forest (RF). The trained ML models can predict the tribological behavior from material variables and test conditions, beyond what is possible from two-parameter correlations. GBM outperformed other ML algorithms in predicting friction behavior, while RF had the best prediction of the wear behavior. ML analysis identified graphite content and hardness and as the most significant variables in predicting the COF, while graphite content and sliding speed were the most dominant variables for wear-rates.

Influence of WC content on microstructure and mechanical properties of Mo2FeB2-based cermets fabricated by multi-step sintering

Herein, Mo2FeB2-based cermets, with nominal composition of Mo2FeB2-2.06Fe-2.9Ni-2.5Cr-xWC-0.04C (x = 0, 2.5, 5, 10 wt %), are fabricated by multi-step sintering to investigate influence of tungsten carbide (WC) content on microstructure and mechanical properties. Results reveal that the microstructure of WC-free cermets resembles that of traditional cermets. However, microstructure of WC-containing cermets (x = 2.5 wt %) is composed of fine black core/grey rim Mo2FeB2 grains and coarse white-colored coreless Fe3(W,Mo)3C grains. Furthermore, at x ≥ 5 wt %, most of white coreless Fe3(W,Mo)3C grains are transformed into a white core/black rim structure. From these observations, it can be concluded that growth of nearly round-shaped Mo2FeB2 grains is through diffusion-control, leading to normal grain growth (NGG), whereas the growth of polyhedral Fe3(W,Mo)3C grains is dictated by the interfacial reactions, resulting in 2D nucleation and partially abnormal grain growth (AGG). In addition, grain size distribution of WC-containing cermets exhibits distinct bimodal characteristics, where average grain size is smaller than that of WC-free cermets. More importantly, presence of WC significantly improves the mechanical properties, resulting in superior fracture toughness of 25.1 ± 0.5 MPa m1/2 and hardness of 90.3 ± 0.1 HRA, at x = 5 wt %, without compromising much of transverse rupture strength.