TiB2 Materials Research Articles

Comparative study of EDM on titanium diboride ceramic material using different electrode materials and dielectric fluid

Abstract Titanium diboride is a highly used material in aerospace industry due of its remarkable longevity. Its strength poses a problem to traditional machining methods. We want to improve the EDM process parameters in TiB2 material by comparing two different dielectric fluids and four different electrode materials. The input parameters were adjusted to find the optimal combination. By studying the fluctuations of output parameters such as MRR, TWR, SR and overcut when processing titanium diboride, researchers can gain valuable insights. This is achieved through experimental studies and the results are then verified using a theoretical regression model. Experimental results confirmed that discharge current, voltage and Ton had a remarkable influence on MRR, TWR and surface roughness in TiB2 material. It has been observed that tool wear rate when using kerosene-based dielectric fluids is higher than that of deionized water-based dielectric fluids. Tungsten copper electrodes cause slightly less tool wear than tungsten electrodes, and produce higher MRR overall, when compared to other three electrode materials. Using a dielectricand a copper electrode can help you obtain a smoother surface. When deionized water is used as adielectric fluid with tungsten electrodes, the crossover value drops dramatically. Brass electrodesproduce ahigher overcut value compared to the other three electrode materials. The microstructure of the EDM hole was distinguished by SEM analysis, and the material composition of TIB2 was determined by EDS analysis

Laser powder bed fusion of TiB2-modified Cu15Ni8Sn alloy: Processability, microstructure and mechanical performance

Cu15Ni8Sn is widely used in the aerospace and electronics domains because of its good conductivity and toughness. Due to the material's high laser reflectivity and thermal conductivity, however, employing the laser powder bed fusion (LPBF) additive manufacturing process on Cu15Ni8Sn alloy has been a challenge. This issue was addressed in the present study by modifying the Cu15Ni8Sn powder by adding 1 wt% submicrometre TiB2 ceramic particles. The results indicate that the LPBF's processability was improved by the increased laser absorption rate caused by the addition of 1 wt% TiB2, which eliminated pores and unmelted area defects. The addition of 1 wt% TiB2 also improved the components' surface quality by reducing the surface roughness value of 39.3% compared to the original Cu15Ni8Sn. The findings also indicate that the added TiB2 particles reduced Sn-segregation behaviour, implying that the content and size of the segregated phase could be tailored by the suitable selection of ceramic materials and LPBF process parameters. Another advantage lies in the enhancement of mechanical performance, where a 11% increase in yield strength and 14% increase in ultimate tensile strength were achieved in the LPBF-fabricated modified Cu15Ni8Sn material. In this study, the primary strengthening mechanisms for LPBF-fabricated original Cu15Ni8Sn were found to include dislocation strengthening and grain boundary strengthening. Orowan precipitation strengthening also played a significant role in the Cu15Ni8Sn-1wt.% TiB2 material, as did dislocation strengthening and grain boundary strengthening. These findings provide a promising strategy to improve the LPBF processability of the advanced copper-based materials used in several key fields.

The Structure and Properties of 65 wt.% Fe–35 wt.% FKh800 Chromium Carbide Steel Doped with Titanium Boride Additions

The effect of TiB2 additions on the structure, phase composition, and mechanical and tribological properties of materials in the Fe–FKh800 system was studied. The introduction of titanium boride additions activated compaction of the iron-based composites through sintering with participation of the liquid phase that emerged with the formation of low-melting Fe–C–B (Tm ~ 1050°C) and γ-Fe–Fe2B–TiB2 (Tm ~ 1162) eutectics and led to a 50–70°C decrease in the sintering temperature of the compacts. Titanium boride additions between 0.38 to 0.74 wt.% provided 20–25% higher bending strength of the 65 wt.% Fe–35 wt.% FKh800 composite with a slight increase in hardness. Metallographic studies, X-ray diffraction, and electron microprobe analysis of the Fe–35 wt.% FKh800–TiB2 materials showed that titanium boride additions promoted a multiphase, microheterogeneous matrix-reinforced composite, consisting of Kh17 chromium steel, double M7C3 and M3C iron–chromium carbides, and complex Me3(CB) carboborides. The influence of TiB2 additions on the wear resistance of the composites subjected to dry friction against fixed diamond wheel particles and ShKh15 steel was studied. The study showed that the abrasive mass wear (Im) of carbide steels decreased from 36.94 to 14.8 mg/km and their linear wear (Il) decreased from 0.197 to 0.079 mm/km with TiB2 additions increasing from 0.38 to 1.48 wt.%. Titanium boride additions ranging from 0.38 to 2.2 wt.% reduced the mass wear rate from 4.9 to 1.9 mg/km in dry friction of the composite against a ShKh15 steel counterface with 50–55 HRC hardness and decreased the friction coefficient from 0.49 to 0.38.

Elaboration and Characterization of the Nanometric Titanium Diboride Powders by Mechanical Milling Method

The research activities are oriented towards elaborating and characterizing nano-sized powders by powder metallurgy technologies based on wet milling in a planetary mill. For the elaboration of the TiB2 powders, a wet milling regime of initial powders was used up to nano size with the following parameters: milling technology by collision, milling times, rotational speed. The characterization of the TiB2 material will include particle size distribution analysis. EDXS and SEM analysis were used to study the structural evolution of the powder after ball milling. The mechanical milling technology, by its milling regimes, proved to be very efficient, obtaining a reduction of the titanium diboride powders particle size up to 50% compared to the initial unmilled powders.

Preparation and microstructure of 3D framework TiC–TiB2 ceramics and their reinforced steel matrix composites

An efficient method for in-situ fabrication of a three-dimensional framework based on heterogeneous TiC–TiB2 materials with different B4C content has been reported in the present study. Interpenetrating TiC–TiB2/steel composites were subsequently prepared by infiltrating molten steel into TiC–TiB2 framework. The XRD and SEM analyses confirmed that three-dimensional ceramics framework mainly consisted of heterogeneous TiC–TiB2 phases with the ceramic particles closely connected with each other. TiC–TiB2 ceramics framework exhibited a high porosity in the range 87.11%–95.95% and low bulk density of 0.17–0.22 g/cm3. The sample with ceramic framework containing 20 wt% B4C exhibited the strongly continuous microstructure, whereas the sample with ceramic framework containing 25 wt% B4C had the weakly continuous framework. The Vickers hardness and fracture toughness in the composites reached 284.5 HV and 23.7 MPa m1/2, respectively. An optimal TiC: TiB2 mass ratio of 37:55 could effectively inhibit the decomposition of TiB2 in the molten steel. Inspecting the fracture surface, the dominated fracture modes was noted to be the quasi-cleavage and trans-granular dimple fracture, which could be attributed to novel three-dimensional bi-continuous structure formed between ceramic framework and steel substrate.

AlMgB14–TiB2 composite materials obtained by self-propagating high-temperature synthesis and spark plasma sintering

In this work, AlMgB14–TiB2 composite materials were obtained by thermochemical-coupled self-propagating high-temperature synthesis (SHS) and subsequent spark plasma sintering. The mechanism was proposed for the formation of the composite materials in the thermochemical-coupled SHS mode. The phase composition, microstructure, and properties (density and Vickers hardness) of the dense AlMgB14–TiB2 materials were investigated. At a sintering temperature of 1470 °C, AlMgB14 is decomposed into AlB12 and Mg. The sample sintered at 1470 °C with a holding time of 5 min had a maximum average hardness of 32.1 GPa.

Microstructural Characteristics and Mechanical Behaviour of AA7075/TiB<sub>2</sub> Composite

Titanium Boride (TiB2) particles reinforced with aluminum alloy (AA 7075) composites were developed using the two-step stir casting method. TiB2 with aluminium alloy was varied in 5, 10, 15 weight percentages (wt.%) . The mechanical properties of the composites were assessed through density, hardness, tensile and impact. Factography observations were also evaluated with Scanning Electron Microscopy (SEM) and phase identification of the composite was carried out through X-ray diffraction technique (XRD). The XRD pattern of alloy and composites revealed peaks of Al and TiB2 particles and the intensity of TiB2 particles increased with increase in wt. %. Compared to the base matrix, the density and hardness of composites increased with the wt. % of TiB2. Addition of TiB2 particles exhibited grain refinement, thereby improving the mechanical properties. Composite materials exhibited high load bearing capacity due to the strong bonding of TiB2 and matrix material resulting in increased impact energy. The tensile strength of the composite increased with increasing wt. % of reinforcement. The failure in the composites observed were dimpled structure and ridges, voids, and cracks.

Highly textured and strongly anisotropic TiB2 ceramics prepared using magnetic field alignment (9T)

Highly textured TiB2 ceramics were prepared by slip casting an aqueous suspension in a magnetic field of 9 T, followed by sintering using Field Assisted Sintering Technology (FAST). Particle size refinement by ball milling improved both the degree of texturing and densification of the material (RD > 98 %). The sintered material exhibited a Lotgering orientation factor of 0.90, with the c-axis of TiB2 oriented parallel to the magnetic field and FAST pressing direction. The texturing effect induced by the uniaxial pressing was negligible. The textured TiB2 material exhibited a significant anisotropy in mechanical properties; the values of hardness and indentation elastic modulus measured along directions transverse to the c-axis of TiB2 were 37 % and 13 % higher than the ones measured along the c-axis direction. Moreover, the specific wear rate of a surface of textured TiB2 parallel to the field was one order of magnitude lower than a surface perpendicular to the field.

Surface characterisation and wettability of titanium diboride by aluminium at low temperature

ABSTRACTTitanium diboride (TiB2) represents a perspective material for innovations in aluminium technology. This refractory ceramic material has superior thermal and electrical conductivity and considerable chemical stability at high temperatures (>1000°C). Furthermore, excellent wettability by molten aluminium at operating temperatures is required for the application of TiB2 as an inert cathode in aluminium electrolysis process. The wettability of various TiB2-based materials has been studied in literature at different conditions in temperature ranges above to 1000°C. The present paper surveys the current state of knowledge on aluminium wettability of TiB2 at high temperatures and examines the wettability of pure hot-press sintered TiB2 material with different values of surface roughness at low temperatures, i.e. below 900°C.

Mechanically activated combustion synthesis of molybdenum borosilicides for ultrahigh-temperature structural applications

The thermal efficiency of gas-turbine power plants could be dramatically increased by the development of new structural materials based on molybdenum silicides and borosilicides, which can operate at temperatures higher than 1300 °C with no need for cooling. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. Materials based on Mo5SiB2 (called T2) phase are promising materials that offer favorable combinations of high temperature mechanical properties and oxidation resistance. In the present paper, T2 phase based materials have been obtained using mechanically activated self-propagating high-temperature synthesis (MASHS). Upon ignition, Mo/Si/B/Ti mixtures exhibited a self-sustained propagation of a spinning combustion wave, but the products were porous, contained undesired secondary phases, and had low oxidation resistance. The “chemical oven” technique has been successfully employed to fabricate denser and stronger Mo5SiB2–TiC, Mo5SiB2–TiB2, and Mo–Mo5SiB2–Mo3Si materials. Among them, Mo5SiB2–TiB2 material exhibits the best oxidation resistance at temperatures up to 1500 °C.

Layered titanium diboride: towards exfoliation and electrochemical applications.

Layered transition metal diborides (TMDB), amongst other refractory metal borides, are commonly employed for material fabrication such as wear- and corrosion-resistant coatings due to their impressive chemical stability and thermal conductivity. In spite of the wide scope of studies carried out on TMDB in the physical field, investigations on its electrochemistry remain limited. Since the physical properties play a vital role in any material's electrochemical behaviour, we explore the viability of the most popular form of titanium boride, layered TiB2, as catalysts for electrochemical energy reactions, including hydrogen evolution and oxygen reduction. Three types of TiB2 were compared in this work - TiB2 separately modified with sodium naphtalenide and butyllithium in an attempt to exfoliate TiB2 and unmodified TiB2. The electrocatalytic activity displayed by all three TiB2 materials provides a wider range of opportunities for the application of TiB2 in material studies.

AlMgB14–TiB2 synthesized by a two-step heat-treatment method

Superhard materials AlMgB14–xTiB2 disks were synthesized by a two-step heat-treatment method. In the first step, AlMg6B14–xTiB2 disks were fabricated by uniformly mixed Mg, B, Al powders and different contents Ti powder, and then AlMg6B14–xTiB2 disks were heated at 850°C for 2h in closed argon atmosphere. In the second step, AlMg6B14–xTiB2 disks were sintered at 1050°C for half an hour in vacuum, then target AlMgB14–xTiB2 disks were obtained. The phase, microstructure and superconductivity were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and superconducting quantum interference device (SQUID). The nano-scale TiB2 particles as the second phase induced by Ti doping are uniformly distributed in the sample matrix. The results reveal that the stepwise synthesis method can produce practical AlMgB14–TiB2 materials.

Comparative study of reactive and non-reactive sintering route for producing B6O–TiB2 materials

Abstract Boron suboxide (B 6 O) based materials containing TiB 2 additions were produced in this study via two routes (non-reactive and reactive sintering) and were consolidated using a hot press, which was operated between the temperatures of 1800–1900 °C and at an applied pressure of 50 MPa for 20 min dwelling time. Relationships between the formed phases, microstructures and mechanical properties of the sintered materials were established. The density was higher in the reactive sintered materials with finer microstructure than in the non-reactive sintered counterpart. Generally, the mechanical properties of the B 6 O–TiB 2 materials were enhanced when compared to the pure B 6 O material.

Analysis of the Solidification and Microstructure of Two Aluminium Alloys Reinforced with TiB2 Particles

AbstractTwo aluminium alloys with 6 wt% TiB2 particles are studied for applications where increased wear resistance and mechanical strength at high temperature are required. The incorporation of hard ceramic particles has a strong influence on the microstructure and properties of the alloys. TiB2 particles play an important role in the nucleation of the different phases of the alloys during solidification, and in the reduction of grain size and porosity. The solidification patterns of Al‐Si7Mg0.3 + TiB2 (6 wt%) and Al‐Cu5MgTi + TiB2 (6 wt%) materials are compared to their corresponding non‐reinforced alloys, and the microstructures are analyzed.

ChemInform Abstract: Design, Operation and Electrochemical Aspects of Hall-Heroult Cells Containing Solid Wetted Cathodes: A 30-Year Chronicle

Abstract The investigation of solid cathodes for aluminum reduction cells dates back to the late 1950's. These early tests showed that substituting a wetted stable cathode for the turbulent metal cathode allows the anode-cathode distance (ACD) to be decreased with an attendant voltage reduction of about IV, depending on current density. Since high efficiency is retained, specific energy consumption is decreased by about 20%. These savings are not as great as anticipated, however, because the effective electrical resistivity of the electrolyte increases as the ACD is lowered. This effect is related to the void fraction of anode gas in the interpolar space. Although TiB2 materials are available that withstand the harsh chemical environment, cell working operations result in an inordinate amount of part breakage. From an operational viewpoint the ideal cathode material would be a durable TiB2 composite coating that could be troweled onto conventional cathode (carbon) blocks.

Electroerosion behavior of a ceramic based on boron carbide: Phase composition, structure, and properties of protective spark coatings

Measurements have been made on the erosion resistance of B4C-15% TiB2 materials made by reactive sintering on hot pressing of B4C-TiO2-C powder mixtures. The composite material is used as an electrode for treating steel and titanium surfaces in spark alloying. It is shown that the method of preparing the boron carbide influences the erosion resistance of the ceramic much less than it does for the mechanical properties. The surface layers of the electrode materials are affected by the electrical discharge and give rise to secondary structures because of chemical interaction between the electrode materials on the one hand and elements in the gas medium on the other. The properties of these structures are responsible for the erosion characteristics of the electrode material and for the compositions and qualitative properties of the coatings.

Processing and Properties of TiB2 with MoSi2 Sinter‐additive: A First Report

The densification of non‐oxide ceramics like titanium boride (TiB2) has always been a major challenge. The use of metallic binders to obtain a high density in liquid phase‐sintered borides is investigated and reported. However, a non‐metallic sintering additive needs to be used to obtain dense borides for high‐temperature applications. This contribution, for the first time, reports the sintering, microstructure, and properties of TiB2 materials densified using a MoSi2 sinter‐additive. The densification experiments were carried out using a hot‐pressing and pressureless sintering route. The binderless densification of monolithic TiB2 to 98% theoretical density with 2–5 μm grain size was achieved by hot pressing at 1800°C for 1 h in vacuum. The addition of 10–20 wt% MoSi2 enables us to achieve 97%–99%ρth in the composites at 1700°C under similar hot‐pressing conditions. The densification mechanism is dominated by liquid‐phase sintering in the presence of TiSi2. In the pressureless sintering route, a maximum of 90%ρth is achieved after sintering at 1900°C for 2 h in an (Ar+H2) atmosphere. The hot‐pressed TiB2–10 wt% MoSi2 composites exhibit high Vickers hardness (∼26–27 GPa) and modest indentation toughness (∼4–5 MPa·m1/2).

Unlubricated fretting wear of TiB2-containing composites against bearing steel

Fretting tests under dry unlubricated conditions (22 °C to 25 °C, 50 to 55 pct RH) were performed on monolithic TiB2, TiB2-based cermet with a Ni3(Al,Ti) binder, sialon-TiB2, and ZrO2-TiB2 composites to assess their relative wear performance against bearing-grade steel. Based on the measured friction and wear data, the relative ranking of the investigated fretting couples is established. The fretting wear of all investigated tribocouples was found to fall in the tribochemical wear regime. The extent of the tribochemical reaction was observed to be strongly dependent on the chemical solubility of TiB2 and the binder phases in steel at the tribocontacts and was accompanied by tribo-oxidation. For the monolithic TiB2 and TiB2-based cermet materials, however, abrasion and adhesive wear, in addition to the tribochemical reactions, are found to be the cause for the high volumetric wear loss of these tribosystems. On the other hand, mild abrasion coupled with reduced tribochemical reactions is observed to play a major role in the low wear loss of the ZrO2-TiB2/steel fretting couple. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis of the tribochemical layer formed in the monolithic TiB2/steel tribocouple revealed the formation of mixed oxides containing predominantly TiO2 (anatase), B2O3, and Fe2O3. Based on the thermodynamic calculations and the experimental observations, a tribochemical wear model is proposed to explain the observed tribological behavior of the investigated tribosystems.

The corrosion behaviour of titanium diboride in neutral chloride solution

The corrosion of a dense TiB2 material (hot pressed with 1.5 wt.% Ni as sintering aid) in 3.5% NaCl aqueous solution was studied at T=25°C, T=45°C, T=65°C for exposure times up to 30 days. Results revealed by polarization curves, polarization resistance measurements and potentiostatic tests, coupled with microstructure analyses of the sample surface and chemical analyses of the solutions after the corrosion tests, allowed us to asses that TiB2 behaves like a passive metal at 25°C and 45°C as a rather protective hydrated titanium oxide film forms, the film protectivity is markedly reduced at 65°C, the corrosion attack is preferentially localized on a Ni-rich grain boundary phase, besides electrochemical corrosion, chemical corrosion also occurs, which plays an important role in the whole corrosion process as long as passive conditions are maintained.

Structure and Properties of Composite Electrospark, Laser, and Magnetron Deposited AlN ― TiB2 Coatings

A comparative investigation of the coatings produced by electrospark alloying, laser gas-powder deposition, and magnetron sputtering using composite AlN ― TiB2 material was carried out. It is shown that the presence of oxygen in the working atmosphere is responsible for the oxidation of aluminum nitride, and also the appearance of refractory compounds of the Ti ― Al ― O system in the coatings. During electrospark and laser alloying globular regions form on the surface by a mechanism of liquid-phase sintering, due to the mass transport of a metallic component from the substrate. The composite layer of a magnetron coating sinters by a mechanism of solid-phase interaction. The dispersion-strengthened structure of electrospark coatings is highly wear resistant, while the continuity, high dispersion, and heterogeneity of the structure of magnetron coatings permits their recommendation for corrosion protection.