Fe Binder Research Articles

Experimental investigation and thermodynamic analysis of TiC–Fe cermets with Mo additions

Abstract In this study, the effects of Mo additions on the microstructure, hardness and bending strength of TiC–Fe cermets manufactured by spark plasma sintering were investigated by scanning electron microscopy, X-ray diffraction and mechanical properties tests. Thermodynamic calculations were utilized to analyze the evolution of the microstructure. The results show that the conventional core/rim structure was not formed during the solid-phase sintering of TiC–Fe cermets. The heat-treatment process and reasonable Mo addition can effectively enhance the overall performance of the alloys. With the addition of minor Mo, the hardness of the sintered cermets improved significantly, which was attributed to the solid solution strengthening mechanism of Mo in Fe binder. However, excessive Mo exceeded the solubility range of Fe binder and precipitated in the form of M 6C and Mo2C phases, which damaged the bending strength of the heat-treated cermets.

A Review of Research Progress on Ti(C,N)-Based Cermet Binder by Intermetallic Compounds and High-Entropy Alloys.

Ti(C,N)-based cermet is a kind of composite material composed of a metal binder phase and a Ti(C,N)-hard phase, which is widely used in the fields of cutting machining and wear-resistant parts due to its high hardness, good toughness, wear resistance, and chemical stability. In recent years, the research on the replacement of traditional Ni, Co, and Fe binder phases by novel binder phases such as intermetallic compounds and high-entropy alloys has made remarkable progress, which significantly improves the mechanical properties, wear resistance, corrosion resistance, and high-temperature oxidation resistance of Ti(C,N)-based cermets. This paper reviews the latest research results, summarizes the mechanism of the new binder to improve the performance of metal-ceramics, and looks forward to the future research directions.

Microstructure, interfacial characteristics, and wear performances of Cu–Fe–SiC cermet composites

AbstractThe Cu–Fe metal‐based ceramic grinding wheel material with SiC as abrasive was prepared by the powder metallurgy process of ball milling and hot pressing sintering. Cu–Fe–SiC cermets with Cu:Fe mass ratios of 4:1, 1:1, and 1:4 were designed by changing the composition of metal binder. The phase composition, microstructure, mechanical properties, and grinding properties of Cu–Fe–SiC cermets were systematically studied. The effect of Cu–Fe binder ratio on the microstructure and properties of cermets was analyzed. The results show that with the increase of Fe content, the density and hardness of cermets increase gradually, indicating that the mechanical properties are improved. Because the Fe in the adhesive can react with the abrasive SiC to form the reaction bonding interface, the Cu–80Fe–SiC cermets with higher Fe content have better adherence. The grinding test results of Cu–80Fe–SiC cermet show that the friction coefficient is .341, the surface roughness is 6.64 μm, the residual stresses parallel to the grinding direction are 353.3 MPa, and the residual stresses perpendicular to the grinding direction are 140.9 MPa. With the increase of Fe content, the wear mechanism changes from ploughing and cutting to friction.

Passivation and Corrosion Behavior of Cemented Carbides in Synthetic Mine Water: Effect of Ni and Fe Binder

Passivation and Corrosion Behavior of Cemented Carbides in Synthetic Mine Water: Effect of Ni and Fe Binder

Effect of Mo<sub>2</sub>C Addition on the Microstructure and Properties of TiC-High Manganese Steel-Bonded Carbide

TiC-high manganese steel-bonded carbide was prepared by powder metallurgy method with varied Mo2C content (0, 2.5%, 5%, 7.5% and 10% respectively), and the effects of Mo2C addition on the microstructure and mechanical properties of the fabricated cermets were studied. The microstructures of the fabricated cermets were observed and analyzed by scanning electron microscope (SEM), and the physical and mechanical properties of the cermets were also tested. The results show that the microstructure of the cermet without Mo2C additive was finer than that of the cermets with 2.5% and 5% Mo2C addition, though Mo2C was an effective grain growth inhibitor of TiC- and/or TiCN-based refractory materials because of low inherent solubility of TiC in Fe binder. An interesting phenomenon was also found that black core-gray rim was observed in the microstructure of the cermet without Mo2C addition. The microstructure of the fabricated cermets was fine with the increase of Mo2C content. The results also show that the relative density and hardness of the cermet increased monotonously with the increase of Mo2C content, hence, the transverse rupture strength (TRS) and impact toughness (IM) of the fabricated cermets increased first and then decreased, and the TRS and IM reached the maximum valve of 2189 MPa and 11.7 J/cm2 when Mo2C content was 7.5% and 5% respectively.

Impact response of a tungsten heavy alloy over 23–1100 °C temperature range

Impact response of a tungsten heavy alloy (WHA) prepared by liquid phase sintering of tungsten powder (∼80 vol. %) with an Ni–Co–Fe (3.50–1.25–1.0 weight ratio) binder was studied over a 23–1100 °C temperature range in a series of planar impact tests accompanied by continuous monitoring of the velocity of the WHA sample rear surface. The temperature dependence of the proof stress Y0.1(T) was found based on the 1D numerical simulations of the performed impact tests using a modified Steinberg–Cohran–Guinan constitutive model, and the temperature dependencies of the density ρ0(T) and longitudinal cl(T) and bulk cb(T) speeds of sound were found using rule of mixtures. The bulk speed of sound cb(T) was also used in determination of the temperature dependence of the spall strength σsp(T) of the alloy based on the experimentally recorded velocity pull-backs Δupb. The strong decrease of both Y0.1(T) and σsp(T) with temperature (Y0.1 decreases almost sixfold between 23 and 1100 °C) allows one to assume that the tensile (spall) fracture of the alloy is controlled by the strength of its matrix.

Hardening of Ti(CN)–Fe composites by microstructural refinement and solid solution strengthening of metallic phase

Ti(CN)–Fe composites were hardened by refining their microstructure and strengthening their metallic phase. The microstructure of Ti(CN)–Fe composites fabricated by the spark plasma sintering of nanocrystalline Ti(CN)–Fe composite powders at a low temperature (1200 °C) for a short duration (5 min) was found to be finer and more uniform than that of conventional composites prepared by sintering at high temperature for a long duration. The composite powders contributed to the prevention of coalescence of Ti(CN) grains; the Ti(CN) grains in the ultrafine composites exhibited a smooth surface, unlike the rough surface of the Ti(CN) grains in the conventional composites. In addition, the mean free path of the Fe binder was shorter in the ultrafine composites than in the conventional composites. The amount of Ti in the Fe matrix was found to be approximately five times higher in the ultrafine composites than that in the conventional composites because there was insufficient time for the reprecipitation of the Ti dissolved in the Fe matrix during the cooling stage of the former. The uniform microstructure with reduced grain size, short Fe binder mean free path, and solid-solution strengthening of the Fe binder by the Ti solute contributed to the enhanced hardness (16.9–18.0 GPa) of the ultrafine composites compared to that of the conventional composites (less than 12 GPa). Finally, it was concluded that Ti(CN)–Fe composites can be hardened by low-temperature/short-time sintering of nanocrystalline composite powders, and the hardened composites could broaden the range of use of Ti(CN)-based composites in mechanical parts.

Interface characteristics in cemented carbides with alternative binders

Cemented tungsten carbides with Co, Ni or Fe binders were studied by transmission electron microscopy. Particular attention was paid to phase and grain boundaries. A striking feature is the high frequency of coherent carbide/binder interfaces with Fe. The Fe rich binder adopts an epitaxy orientation relationship with prismatic facets of WC, with a parametric misfit of about 1.5%. A special orientation relationship with basal facets of WC grains is sometimes observed with Ni binder, as already noticed for Co. It is associated with a parametric misfit of about 15%. Binder segregation in WC grain boundaries was studied taking into account the effect of carbon content in the alloys. Whatever the binder, no influence of the carbon content could be pointed out. The analyses performed in random grain boundaries in WC-Co alloys agree with the literature value of 0.5 monolayer of segregated Co while slightly larger values are obtained for Ni and Fe binder. ∑ = 2 special grain boundaries were studied in WC-Co and WC-Ni alloys and no segregation was detected. The higher grain boundary segregation as well as the occurrence of coherent interfaces should influence the mechanical properties of WC-Fe alloys.

Densification, microstructure and mechanical performance of TiC/Fe composites by spark plasma sintering

In this study, the effects of the TiC content (10, 20, 30 and 40 vol. %) on the densification, microstructure, mechanical performance and friction properties of TiC/Fe composites were investigated. The combination of powder metallurgy (PM) method and spark plasma sintering (SPS) was used to prepare high-density TiC/Fe composites. The results show that the TiC/Fe composites experienced the dominating densification below 600 °C. The subsequent densification was restricted by the limited diffusion and dissolution between the TiC particles and Fe matrix, which has been verified by thermodynamic calculations in the present work. The hardness and bending strength of TiC/Fe composites improved until the maximum value, and then followed a decreasing trend with TiC content further increasing. The 20 vol. % TiC/Fe composite reached the highest bending strength of 1318 MPa, while the maximum hardness of 36.0 HRC was attained for the composite with 30 vol. % TiC. Fe binder plastic tearing, transgranular failure and intergranular failure were the main fracture mechanisms of TiC/Fe composites. In addition, the specific wear rate of the TiC/Fe samples increased with increasing TiC content, which should be ascribed to the severe oxidation of worn surfaces under load of 10 N and slide distance of 800 m.

Sintering mechanism, microstructure evolution and nanomechanical properties of Cr-added Mo2FeB2 based cermets

Mo2FeB2 based cermets with xCr (x = 0, 3, 6, 9, 12, weight %) contents were fabricated via reaction boronizing sintering strategy. Effects of Cr addition on sintering mechanism, microstructure evolution, and nanomechanical properties of Mo2FeB2 based cermets were investigated. Results indicate that the addition of Cr decreased reaction temperatures of solid-phase and liquid-phase reactions in sintering process. Moreover, relatively small grain size of Mo2FeB2 hard phase and maximum relative density of Mo2FeB2 based cermets were obtained at 9 wt% Cr content. Besides, Cr atoms replaced partial Mo atoms in Mo2FeB2 hard phase and partial Fe atoms in Fe binder phase, respectively. In addition, the Mo2FeB2 grains transformed from anisotropic shape to isotropic shape with Cr solution. High resolution TEM revealed that with Cr addition, interplanar distance of Mo2FeB2 crystal decreased, while interplanar distance of Fe crystal increased. More edge dislocations and lattice distortions occurred in cermets with 9 wt% Cr content as compared with Mo2FeB2 based cermets without Cr. Furthermore, intrinsic hardness, elasticity modulus, and resistance to plastic deformation of Mo2FeB2 hard phase and Fe binder phase enhanced with Cr content increasing from 0 wt% to 12 wt%. However, intrinsic toughness decreased in the process.

Die-less manufacturing of tube by diffusion bonding of unit rods made of tungsten heavy alloy

A die-less method to manufacture tubes by diffusion bonding of rods made of tungsten heavy alloys was developed and characterized. Tungsten heavy alloys are pseudo-alloys of tungsten (W) with small amounts of lower-melting-point binder metals, typically Ni and Fe, and they are widely used in tubular shapes. Due to the excessively high consolidation temperature for W, the fabrication of components is normally done by sintering of powder compacts. During the sintering of W–Ni–Fe alloys, the partially melted Ni–Fe binder metal wets the tungsten powder particles and provides a soluble diffusion network for rapid sintering. However, as the binder metals partially liquefy, this process results in gravity-induced slumping, leading to distortion near the bottom section of the tubular part. This gravity-induced slumping creates significant difficulties during the production of tubular structures. A rod shape is the most stable shape to avoid slumping during sintering. Thus, a method to manufacture tubular tungsten heavy-alloy parts via joining of sintered rods by diffusion bonding was developed. Using an analytical model, the dimensions of the unit rods for fabrication of the target tube shape have been designed. An industry-applicable tube manufacturing process was well characterized, and the feasibility of the process was confirmed.

Growth and Properties of TiN/Al2O3/Ti(C, N)/TiN Multilayer CVD Coatings on Ti (C, N)-Based Cermet Substrates with Ni, Co and Fe Binders

In this article, Ti (C, N)-based cermets with Ni, Co and Fe binder phase were manufactured by traditional powder metallurgical techniques. The multilayer TiN/Al2O3/Ti (C, N)/TiN CVD (chemical vapor deposition) coatings were deposited on the three kind of cermets, and the growth and properties of the coatings were studied. The results show that massive cores-incomplete rims are found in the cermet-Ni (cermets with Ni binder) and cermet-Fe (cermets with Fe binder), while in the cermet-Co (cermets with Co binder), the small black cores are surrounded by a complete and well-developed rim phase. When the TiN coating is deposited on the cermets with cores-incomplete rims, the Ti and N atoms stack on the face-centered cubic structure of Ti (C, N) first, and epitaxial growth of the TiN crystals takes place. The epitaxial growth is attributed to the same preferred orientation (2 0 0) of the TiN layers to the Ti (C, N) of the substrate. While on the cermets with cores-complete rims, (Mo, Ti) (C, N) solid solution and binder phase (Ni/Co/Fe), which has a distinct crystal structure or lattice parameters, TiN grains nucleate first and then grow. In this case, the TiN coatings show a (1 1 1)-oriented structure. Dense and thin coatings grow on the cermets-Co. The adhesion of the multilayer coatings to the substrate increases in the order cermets-Fe, cermets-Ni and cermets-Co. In addition, the coating on the cermets-Co has the lowest COF (coefficient of friction) as the thin TiN layer (0.7 μm) is propitious to diffusion of Al and O, and a protective transfer layer is formed by AlOx.

Influence of cemented carbide binder type on wear initiation in rock drilling – Investigated in sliding wear against magnetite rock

Cemented carbides, containing hard WC grains in a ductile Co binder, are commonly used as the rock crushing part of rock drills. They generally work well and show moderate and gradual wear in rock drilling applications. However, due to health issues, an alternative to Co is sought for, which will not compromise the performance. In the present work, the initiation of wear of cemented carbides with the two alternative binders Ni and Fe are investigated and compared to the common Co containing material in a sliding test. The sliding counterpart is magnetite, representing a rock type generally causing slow wear of the cemented carbides.The results show that magnetite is immediately transferred to the cemented carbide thus forming thin layers, mainly on top of the binder, and WC grain fragments are removed. The chain of events is similar irrespective of binder, however the severity shows a strong dependence. The cemented carbide grade with the Ni binder shows relatively rapid wear initiation, compared to that with the Fe binder that shows moderate initiation and that with Co that is barely worn at all.

Effects of metal binder content and carbide grain size on the microstructure and properties of SPS manufactured WC–Fe composites

In the research, an investigation has been carried out on the microstructure and mechanical properties of WC–Fe composites, with various Fe content and either fine- or coarse-grained WC. The WC/Fe composite powders were processed by powder metallurgy method and consolidated to high density by spark plasma sintering (SPS). According to the thermodynamic calculations, the sintering temperature was selected to be 1050 °C. The experimental results indicated that there existed two main phases of WC, α-Fe and one minor Fe3W3C phase in the WC–Fe composites, which was consistent with the thermodynamic calculations. Besides, the relative densities of the composites increased with the Fe binder content, while exhibited different trends for the fine- and coarse-grained composites. Among the WC–Fe hard alloys, the composite with fine-grained WC and 30 wt % Fe binder possessed the highest hardness of 60.5 HRC. The maximum bending strength of 1851 MPa was attained for the composite with coarse-grained WC and 70 wt % Fe binder. The fracture mechanism of the composites was a combination of transgranular failure, intergranular failure, and Fe binder plastic tearing.

Understanding of wetting and solubility behavior of Fe binder on Ti(C,N) cermets

Given the great interest generated in the last years by the searching of new binders in hard materials, a work methodology has been created that allows the design of new metal – ceramic combinations. It includes the study of the solubility between the new binder and the reinforcement during the design of the binder composition combined with the knowledge of the sintering behavior of the cermet by monitoring the contact angle of the liquid phase formed at high temperature.Iron is considered as the main alternative binder in cermets; however, proper compositions are still under development as it is necessary to improve the sintering. This work propose the use of Ni as sintering aid to improve the wettability without the introduction of secondary phases. The article shows a comprehensive study of the high temperature behavior, in terms of solubility and wettability, of the system Fe-Ti(C,N) compared with the study of the conventional system Ni-Ti(C,N). Results show that the highest difference between Fe and Ni binders is the better wetting behavior of Ni binder, but the contact angle of liquid Fe is largely reduced by the addition of a small quantity of Ni. This fact opens the possibility to replace Ni as binder by a less toxic and cheaper binder.

On gradient formation in alternative binder cemented carbides

In this work ICME (Integrated Computational Materials Engineering) has been applied to help understanding gradient formation in today's state-of-the-art cutting tool inserts. The approach was used to carefully design the experimental setup to learn about the controlling mechanisms on gradient formation in Co/Ni/Fe binder systems. The model considers activities, phase fractions and solubilities of diffusing elements in the liquid in these multicomponent systems. It was observed that the gradient thickness is the same for Ti-W-C-N-Co and Ti-W-C-N-Ni at 1410 °C - despite the higher solubility of Ti in liquid Ni compared to Co. This was also true for more complex Ti-Ta-Nb-W-C-N-Co and Ti-Ta-Nb-W-C-N- Fe-Ni at 1410 °C in this study. At 1450 °C the gradient thickness increases for all binders, showing a large increase in the gradient thickness. The thickest gradient was observed for X = Ni in the Ti-W-C-N-X system and thinest for X = Fe binder despite similar N and C activity differences. The Ti-Ta-Nb-W-C-N- Ni-Fe (85Ni-15Fe) had a thicker gradient compared to the Ti-Ta-Nb-W-C-N-C-Co system.

TiC-Fe-Based Composite Coating Prepared by Self-Propagating High-Temperature Synthesis

TiC-Fe-based composite coatings were prepared in situ by self-propagating high-temperature synthesis combined with vacuum expendable pattern casting process. The band-like TiC phase embedded in a continuous Fe binder. There were no obvious defects and impurities at the interface between coatings and matrices. Fe presented consecutively in the coating zones and substrate zones without interruption and the microhardness in the cross-sectional area of the coating–matrix reduces continuously from the coating to the matrix area, indicating a good metallurgical bonding between the coatings and matrices. The effect of casting temperature on the microstructure and hardness of TiC-Fe-based composite coating was investigated in detail. The TiC particles formed at low casting temperature were nearly spherical in shape, and the size of TiC particles increased with increasing casting temperature due to more agglomeration. The hardness of the coatings increased first and then decreased with increasing casting temperature, and reached the highest value of 68 HRC when the casting temperature was 1773 K (1500 °C), which was twice more than that of the matrix.

Preparation and mechanical properties of bulk ultrafine (W0.5Al0.5)C0.65 with minor Fe binder by reactive hot-pressing

ABSTRACTBinderless (W0.5Al0.5)C0.65 produced by reactive hot-pressing (RHP) has high hardness but low bending strength and fracture toughness. In this work, bulk ultrafine (W0.5Al0.5)C0.65 with minor addition of Fe as the binder phase has been prepared by RHP. Rapid synthesis and high densification can be achieved for the (W0.5Al0.5)C0.65 with 0.4–1.0 wt-%Fe by RHP at a relatively low temperature. Pure (W0.5Al0.5)C0.65 without sub-carbide phase or brittle η-type phase can be synthesised due to the fact that the carbon vacancy in (W0.5Al0.5)Cy can reach 50%. And thanks to the combined effect of nanoscaled initial powders, low temperature, rapidly reactive sintering and pressure, bulk ultrafine (W0.5Al0.5)C0.65-Fe with a grain size of about 0.2 μm can be obtained by RHP. Thus, with an appropriate amount of Fe (about 0.8 wt-% in this work), the bending strength and fracture toughness of (W0.5Al0.5)C0.65 can be highly improved.

Briquetting of Waste Silicon Carbide Obtained from Silicon Wafer Sludges

Waste SiC powders obtained from silicon wafer sludge have very low density and a narrow particle size distribution of . A scarce yield of C and Si is expected when SiC powders are incorporated into the Fe melt without briquetting. Here, the briquetting variables of the SiC powders are studied as a function of the sintering temperature, pressure, and type and contents of the binders to improve the yield. It is experimentally confirmed that Si and C from the sintered briquette can be incorporated effectively into the Fe melt when the waste SiC powders milled for 30 min with 20 wt.% Fe binder are sintered at upon compaction using a pressure of 250 MPa. XRF-WDS analysis shows that an yield of about 90% is obtained when the SiC briquette is kept in the Fe melt at for more than 1 h.

Sol–Gel Derived Fe‐Rich Matrix Composites Having Precipitated WC

SEM image of a sol–gel derived composite presenting WC grains (grey phase) embedded in a Fe binder matrix (dark phase). The crystalline composites are prepared from amorphous sol–gel masses containing W, Fe alkoxides and extra carbon. WC and Fe precipitate in-situ out of the WCFeO masses during a two steps heating process under a flux of H2/Ar up to 600–800 °C and then under vacuum up to 1250 °C.