High Hardness Properties Research Articles

Machinability Study of Cemented Carbide Using Focused Ion Beam (FIB) Milling

Focused ion beam (FIB) milling is one of the fastest and accurate processes for the micro- and nanofabrication of devices. There is a need of making micro- and nanoscale components from cemented carbide material due to its favorable properties of high hot hardness and wear resistance. These are the required properties of a microtool during micromachining. Efforts have been put forward to investigate the machinability aspects of cemented carbide by the FIB milling process. Beam current was observed as the significant process parameters of FIB milling process to affect the material removal rate (MRR) and surface roughness on the machined surface of cemented carbide. In addition, extraction voltage, angle of beam incidence, and percentage overlap between beam diameters of adjacent pixels were taken into account to analyze the machinability aspects of cemented carbide by FIB milling. Dwell time was observed as a less significant parameter to affect MRR and surface roughness of cemented carbide.

Effects of SiC nanoparticles orally administered in a rat model: Biodistribution, toxicity and elemental composition changes in feces and organs

BackgroundSilicon carbide (SiC) presents noteworthy properties as a material such as high hardness, thermal stability, and photoluminescent properties as a nanocrystal. However, there are very few studies in regard to the toxicological potential of SiC NPs. ObjectivesTo study the toxicity and biodistribution of silicon carbide (SiC) nanoparticles in an in vivo rat model after acute (24h) and subacute (28days) oral administrations. The acute doses were 0.5, 5, 50, 300 and 600mg·kg−1, while the subacute doses were 0.5 and 50mg·kg−1. ResultsSiC biodistribution and elemental composition of feces and organs (liver, kidneys, and spleen) have been studied by Particle-Induced X-ray Emission (PIXE). SiC and other elements in feces excretion increased by the end of the subacute assessment. SiC did not accumulate in organs but some elemental composition modifications were observed after the acute assessment. Histopathological sections from organs (stomach, intestines, liver, and kidneys) indicate the absence of damage at all applied doses, in both assessments. A decrease in the concentration of urea in blood was found in the 50mg·kg−1 group from the subacute assessment. No alterations in the urine parameters (sodium, potassium, osmolarity) were found. ConclusionThis is the first study that assesses the toxicity, biodistribution, and composition changes in feces and organs of SiC nanoparticles in an in vivo rat model. SiC was excreted mostly in feces and low traces were retrieved in urine, indicating that SiC can cross the intestinal barrier. No sign of toxicity was however found after oral administration.

Fabrication and Surface Hardening Properties for SiC/AlN Ceramic Composites with Different SiC Grain Size

In this research, the SiC/Al/h-BN composite ceramics with different SiC grain size were fabricated by the method of preparing the machinable pre-sintered body through Plasma Activated Sintering (PAS), which has the advantage of complex shape formation for precision parts. By hardening treatment, the SiC/Al/h-BN composite ceramics would be changed to SiC/AlN composites, and the relatively higher hardness and mechanical properties could be obtained accordingly. The phase transformation and microstructure were observed and the mechanical and other properties were also measured. The results showed that, for different matrix SiC particle size, change tendency of the bending strength was different with the heat treatment temperature change. And the bending strength of composites with larger SiC grain size was higher than that with smaller SiC grain size.

Formation Characteristics of High-density and High-hardness New Briquette Based on Herby Biomass

The aim of the Japanese cabinet council's 'Biomass Nippon Strategy' is to increase the utilization of biomass as one of the ways to reduce the dependence on fossil resources. However, there are various problems associated with the use biomass, one of which is the cost associated with the collection and transportation of biomass. Biomass has high moisture content and low bulk density. The biomass solidification technology developed by Ida et al. partly aims to solve the transportability problem. This study shows physical properties of high density and hardness of the new briquette produced from herby biomass. The relationship between apparent density and maximum compressive strength and an effect on the maximum compressive strength by black colorization are considered. Also, an attempt is made to explain the effect on properties of the briquette by hemi-cellulose and lignin in the region before semi-carbonized region. As a result, the relation between the apparent density and the compressive strength shows that maximum value exists as characteristics of the herby briquette. The maximum apparent density for all processing conditions is 1.38 g/cm3 at the initial moisture 0.10 kg/kg-wet - processing temperature 473 K. The maximum compressive strength for all processing conditions is 127 MPa at the initial moisture 0.05 kg/kg-wet - processing temperature 453 K. Furthermore, the effect of black colorization indicates that when the area of black colorization is increased for the surface of herby biomass briquette by increased in the processing temperature, the maximum compressive strength is decreased due to reduction in the adhesion of lignin. Consequently, high-density and high-hardness of the new briquette can be controlled by the initial moisture and the processing temperature.

SANDVIK BIOLINE 20AP

Abstract Sandvik Bioline 20AP is a free-cutting carbon steel with high hardness and good machining properties. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: SA-642. Producer or source: Sandvik Steel Company. See also Alloy Digest CS-145, November 2004.

Self-propagating high-temperature synthesis mechanisms within the Ti–C–Ni system: A time resolved X-ray diffraction study

An experimental study on direct formation of TiC–Ni composite by self-propagating high-temperature synthesis (SHS) was conducted using a Ti–C–xNi systems (x=5, 10, 15wt.%). Composites of this kind are known to exhibit interesting structural and mechanical properties (high strength in shear and compression, high service temperature capabilities), thanks to the combination of metallic (ductility and toughness) and ceramic (high strength, modulus and hardness) properties. X-ray powder diffraction (XRPD) experiments performed on the combustion–synthesized products have shown that the main products were always TiC and Ni acting as a binding phase, but that the reaction might be incomplete in some cases, and the formation of a small amount of Ni–Ti compounds and metastable Ni3C was observed. To understand the chemical pathway, a time resolved X-ray diffraction experiment (TRXRD) using synchrotron radiation (ESRF ID-11, Materials Science Beamline) was performed to follow the reaction in situ on a time scale of ~35ms. This analysis showed that TiC was the first phase to form through solid-state diffusion of C into β-Ti, followed by Ti–Ni melt and finally the simultaneous appearance of metallic Ni and Ni3Ti, suggesting an eutectic reaction during the cooling stage. Using Rietveld refinement, some critical temperatures were estimated via thermal expansion/contraction of the lattice parameter of TiC during the combustion reaction.

A New Type of Submerged-Arc Flux-Cored Wire Used for Hardfacing Continuous Casting Rolls

It is expected that the welding hardfacing of continuous casting rolls has better welding performance and higher wear resistance. A new type of submerged-arc hardfacing flux-cored wire has been developed through nitrogen replacing part of carbon and addition of the nitrogen-fixing elements of niobium and titanium. And microstructure, degree of hardness and high-temperature wear resistance of its deposited metal samples were also investigated. It is found that the microstructure is martensite, residual austenite and carbonitride precipitates. As a result, the hardfacing metal with homogeneous distribution of very fine carbonitride particles had high hardness and excellent wear-resisting property during high-temperature wear, which could significantly extend the service life of continuous casting rolls.

Oxygen modified diamond-like carbon as window layer for amorphous silicon solar cells

Abstract In the present study, the effect of in situ layer-by-layer oxygen plasma treatment (OPT) on optical, nano-mechanical and electrical properties of layer-by-layer diamond-like carbon (DLC) thin films was explored. In situ layer-by-layer OPT on layer-by-layer DLC films led to drastic variation of optical band gap from 1.25 eV to 2.6 eV and hardness from 16.1 GPa to 25.3 GPa. Wide band gap and the band gap feasibility over wide range may lead to its realization as p-type window layer in p–i–n solar cells and variable band gap layers in tandem solar cells. Simulations of a-Si:H based p–i–n solar cells was also carried out by considering OPT–DLC films as p-type window layers that yielded maximum efficiency of 8.9%. In addition, due to high hardness and other excellent nano-mechanical properties, these OPT–DLC films can be treated as hard, protective and encapsulate layers on solar cells particularly in n–i–p configuration. It is important to mention that OPT–DLC film as p-layer can minimize the use of additional hard, protective and encapsulate layer.

Microstructure and mechanical property evaluation of pulsed DC magnetron sputtered Cr–B and Cr–B–N films

CrB2 and four Cr–B–N films with high Cr/B ratio and various nitrogen contents were deposited by a co-sputtering process using a bipolar asymmetric pulsed DC reactive magnetron sputtering system. The structures and BN bonding nature of the thin films were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. The surface and cross sectional morphologies of the thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface roughness of the thin films was explored by atomic force microscopy (AFM). Nanoindentation, microscratch and ball-on-disk wear techniques were used to evaluate the hardness, and tribological properties of the thin films, respectively.The microstructure of the Cr–B–N thin films changed from a coarse columnar structure to a glassy and featureless morphology as the nitrogen content increased from 15.2at.% to 54.5at.%, whereas the corresponding structure developed from an amorphous state to a nanocomposite structure consisting of CrN nanograins and amorphous BN phases. It was found that high hardness, good tribological and brittle properties were obtained for the CrB2 coating. The hardness and elastic modulus of the Cr–B–N thin films decreased with increasing nitrogen content until the nanocomposite structure of nanocrystalline CrN grains and an amorphous BN matrix was formed. However, the hardening effect induced by the nanocomposite structure was limited due to the fact that the small CrN nanograins were surrounded by a thick intergranular soft amorphous BN layer. On the other hand, the fracture toughness and resistance against elastic strain to failure of the Cr–B–N coatings were effectively enhanced by the addition of nitrogen.

Microstructural features and properties of high-hardness and heat-resistant dispersion strengthened copper by reaction milling

The oxide dispersion strengthened copper alloys are attractive due to their excellent combination of thermal and electrical conductivities, high-temperature strength and microstructure stability. To date, the state-of-art to fabrication of them was the internal oxidation (IO) process. In this paper, alumina dispersion strengthened copper (ADSC) powders of nominal composition of Cu-2.5 vol%Al2O3 were produced by reaction milling (RM) process which was an in-situ gas-solid reaction process. The bulk ADSC alloys for electrical and mechanical properties investigation were obtained by sintering and thereafter hot extrusion. After the hot consolidation processes, the fully densified powder compacts can be obtained. The single γ-Al2O3 phase and profile broaden effects are evident in accordance with the results of X-ray diffraction (XRD); the HRB hardness of the ADSC can be as high as 95; the outcomes should be attributed to the pinning effect of nano γ-Al2O3 on dislocations and grain boundaries in the copper matrix. The electrical conductivity of the ADSC alloy is 55%IACS (International Annealing Copper Standard). The room temperature hardness of the hot consolidated material was approximately maintained after annealing for 1 h at 900 °C in hydrogen atmosphere. In terms of the above merits, the RM process to fabricating ADSC alloys is a promising method to improve heat resistance, hardness, electrical conductivity and wear resistance properties etc.

Spraying Distance Dependence of Microhardness on HVOF WC-Co Coatings

Thermal sprayed WC-based coatings are widely used in modern industry, especially in excellent wear-resistant-demanding fields, due to their high hardness and superior mechanical properties. WC-Co is a typical representative of the coatings, usually used as the protective layers of shaft, pump sleeve intine, etc. WC-Co coatings were prepared on low carbon steel substrate using high velocity oxygen fuel (HVOF) technology, under different distance ranging from 160 to 240 mm. The influence of the spraying distance on coating hardness was investigated and discussed. The results reveal that, the cross-sectional hardness of the HVOF WC-Co coatings depend not only on the spraying distance, but also on the indentation position. The average microhardness for all the coatings was obviously enhanced. The highest one (1793.6 Hv) was produced with a distance of 240 mm. Due to the heat effect of the flame, the hardness for all coatings varies with the distance from indentation to coating/substrate interface.

Effect of tensile stress on the formation of S-phase during low-temperature plasma carburizing of 316L foil

Low-temperature plasma carburizing of austenitic stainless steel can produce a carbon-supersaturated austenite layer, the “S-phase”, on the surface, which has high hardness, excellent wear and fatigue properties, and good corrosion resistance. Although the S-phase was discovered some years ago, the basic understanding of S-phase formation remains incomplete. In this paper, the effect of tensile stresses (0–80 MPa) on the formation and stability of S-phase during carburizing of 316L stainless steel foils at 400, 425 and 450 °C for 10 h has been investigated for the first time. The microstructures were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy and the mechanical properties were evaluated by microhardness and tensile tests. The results showed that the in situ applied tensile stress effectively thickened S-phase layers. The calculated activation energy for carbon diffusion in 316L was reduced from 142.76 to 133.91 kJ mol −1 when a tensile stress of 40 MPa was applied. However, chromium carbides were formed in the outmost surface when the tensile stress exceeded 40 MPa. The results are discussed and explained through appropriate thermodynamic calculations.

Study of Properties of Ni-Base Nano-ZrO<sub>2</sub> Composite Plating Coatings

The surface of copper plate of the mold need to be reinforced to obtain the plating coatings with high hardness and corrosion resistant properties. Nowadays, Ni-base alloy coatings is used widely in the industrial production. In order to raise the service life of mold, the experiments on the property of Ni-base nano ZrO2 composite plating coatings was done in this paper. The experiments were planned with the orthogonal test design method. The effective factors on the property of coatings, bath temperature, cathode current density, the distance between two electrodes and the magnitude of Nano-ZrO2,were experimentally studied. The optimum process parameter were obtained. The results show that the composite plating layer of Ni-base Nano ZrO2 with good properties can be obtained.The optimal conditions are as follows: the bath temperature is 40 °C, cathode current density is 3A/dm2, the distance between two electrodes is 12 cm, the magnitude of Nano-ZrO2 is 12g/L. In addition binding strength of the coatings were measured quantitatively, and the structure of the plating layer were observed with SEM. The layer with good properties can be obtained in this method.

A study of TiMoN nano-multilayer coatings deposited by CFUBMSIP using DC and HIPIMS power

TiMoN nano-multilayer hard coatings have been deposited using the closed field unbalanced magnetron sputter ion plating (CFUBMSIP) technique. In one set of experiments, standard DC power supplies were used on four magnetrons in the CFUBMSIP system (4DC magnetrons). The second set of experiments was also in the same magnetic field configuration of CFUBMSIP, but three magnetrons were as again powered with standard DC whilst one magnetron with Ti target was supplied by a high power impulse magnetron sputtering (HIPIMS) power generator (3DC+1HIPIMS magnetrons). Two elemental titanium sputtering targets and two of molybdenum were used to produce the TiMoN nano-multilayer coatings. Analysis of the coatings was carried out to investigate the differences in terms of properties, compositions and microstructures of the coatings deposited by these two sets of experiments. It was found that the coatings deposited by both sets of the experiments exhibited similar properties of high hardness, good adhesion and exceptional wear resistance, with a lower sliding friction than more commonly used hard coatings including TiN, CrN, TiAlN, CrTiAlN etc. Although the initial TiN coating as formed at the coating-substrate interface using the process of 3DC+1HIPIMS magnetrons appeared to show a less oriented microstructure in comparison with that of the coating produced by the process using 4DC magnetrons, the compositions and cross sectional microstructures of the bulk of the coatings did not show significant differences, as observed by the cross sectional Transmission Electron Microscopy microstructures of these two types of TiMoN coatings.

Effect of bipolar pulsed dc bias on the mechanical properties of silicon oxide thin film by plasma enhanced chemical vapor deposition

SiO x thin films synthesized on polycarbonate substrates by low temperature plasma processes are electronically meta-stable because the process temperature (<70 °C) needed to prevent deterioration of the polymer substrate is too low to allow the formation of a thermodynamically stable structure with stoichiometric electronic bonding. Therefore, the surfaces are very active and react chemically with the environment after scratching and pressure. This paper reports a coating method for producing dense structures with high hardness and good optical properties by controlling the ion current density (ion flux). The ion current density (ion flux) on the substrate was controlled by the RF power and additional bias with a bipolar pulsed dc frequency.

Microtool coatings using magnetron sputtering

<title/>This paper presents a deposition process for hard coatings on micromachining cutting tools using closed field unbalanced magnetron sputter ion plating. Any microtools with diameters in the range 0·1-0·5 mm can be coated using this deposition method, with uniform, smooth and ‘defect free’ surface morphology on the cutting corner areas. The coatings, consisting of single or multiple transition metal nitrides or carbonitrides, have also been deposited on the flat, hardened tool steel samples and are shown to have the desirable properties of high hardness, good adhesion and high wear resistance. Evaluation of the coatings and coated microtools is carried out using scanning electron microscopy, microhardness, Rockwell diamond scratch and indentation, and pin-on-disc measurements. Mechanical micromilling is used to test the coatings on WC-Co solid micromills, dry cutting hardened H13 die steel. The results show that this deposition process is capable of producing a range of hard coatings on micromachining tools, with attractive properties and significant improvement of tool lifetime.

TiB 2/Ni coatings on surface of copper alloy electrode prepared by electrospark deposition

In order to improve the lifespan of spot-welding electrodes used for welding zinc coated steel sheets, titanium diboride was deposited onto their surface after precoating nickel as an intermediate layer. The microstructures and phase compositions of TiB 2 and Ni coatings were characterized by SEM and XRD. The coating hardness was measured using a microhardness tester. The results indicate that a satisfactory TiB 2 coating is obtained as a result of the intermediate nickel layer acting as a good binder between the TiB 2 coating and the copper alloy substrate. Owing to its capacity of deforming, the precoated nickel layer is dense and crack free, while cracks and pores are observed in the TiB 2 coating. The hardness of the TiB 2/Ni coating decreases with the increase of voltage and capacitance because of the diffusion of copper and nickel and the oxidation of the coating materials. Because of the good thermal and electrical conductivities and high hardness properties of TiB 2, the deformation of the electrode with TiB 2/Ni coating is reduced and its spot-welding life is by far prolonged than that of the uncoated one.

Fabrication of Magnesium Based Composite Powders with High Hardness and Hard Magnetic Properties by Mechanical Alloying

In order to fabricate Mg-based composite powders with high hardness and hard magnetic properties, pure magnesium and barium ferrite powders were mechanically alloyed (MAed) using a vibrational ball mill.Change in Vickers micro-hardness of the pure magnesium powders as a function of the mechanical milling (MM) times obeyed the crystallite size. Change in Vickers micro-hardness of the composite powders as a function of the amount of barium ferrite obeyed the rule of mixture when the MA time was 120 and 240 min.. On the other hands, change in Vickers micro-hardness of the composite powders as a function of the amount of barium ferrite wasn't obeyed the rule of mixture when the MA time was 20 and 60 min.. Magnetization of the composite powders obeyed the amount of the barium ferrite powder, whereas coercive force of the MAed powders decreased due to the refinement of the barium ferrite powder.Mg-based composite powders with high hardness and hard magnetic properties were successfully produced by mechanical alloying.

F107 高効率バイオコークス専焼ボイラーの開発(OS3 バイオマス・新燃料・環境技術)

Low Carbon Society started based on a new concept by METI in JAPAN. A low carbon project has many programs, transportation or carbonization technologies and dust division motion act etc. Our projects carried out feasibility studies of alternative energy for fossil resources with the new solid bio-fuel, Biocoke. Biocoke has special physical properties of high density and hardness. One of our projects is that this report discusses the mono-fuel combustion boiler developed exclusively for Biocoke. The herbaceous plant, Itadori, is used as a biomass raw material to produce Biocoke. The Biocoke boiler has the hybrid thermal exchange system by hot water and air as itself performance. On the other hand, this project proposed a new thermal energy distribution system based on planter agriculture for high efficient utilization of thermal energy. The total thermal efficiency of Biocoke boiler is 75% over at the maximum. In winter, Biocoke boiler worked in high performance condition during 5 months under the extremely cold environment at -30℃. This project suggested Biocoke is able to completely substitute for fossils resources such as kerosene/heavy oil. Accordingly, this project found that Low Carbon Society can realize by high value added industry and low carbon agriculture under economic action in the winter season.

The Research on Preparation and Machining Performance of Hard, High Strength and Tenacity Wax-Based Material

This paper studies the additive influence on paraffin performance. Paraffin, synthetic wax, vegetable wax, rosin wax and other additives are blended according to certain proportion, and the mixture is modified by amidation process. The hard, high strength and tenacity wax-based material is produced, and its machining performance is studied. The result suggests that the mechanical properties of this material is better than paraffin, it possesses the properties of high hardness, high strength and high ductility and toughness. This material can meet the machining requirements, it is a kind of ideal substitute material for consuming steel in machining technical training. The production of this material can solve the high consumption and high cost problems in application. Steel, one of the known mechanical cutting materials, is widely used as engineering material. But in particular usage, such as the processing technology of universal machine tool, the training of numerical control processing technology and so on, because the cutting workpiece is not used as a forced mechanical component, the steel, as a mechanical material, not only lead to a great waste of a lot of steel, but also lead to the higher wearing of tool and higher consumption of power, which is caused by cutting steel. All of these factors make the machining technology training have been in an operation of high-consumption and high-cost. In China, more than 1000,000 tons steel and more than a billion yuan will be consumed by all kinds of mechanical engineering training in institutions and the skills training for employees machinery manufacturing enterprise. So for construction of a economical society, it has a great significance to develop a substitute material with lower price of raw material and simple preparation equipment and technology, which has no harm to environment and can be recycled repeatedly, and has the same mechanical cutting performance with steel. At present, in foreign countries, the sample wax is produced for mechanical cutting, and in our country, the preparation methods of high hardness wax and the effect of additive on paraffin hardness are introduced by many documents[1-3]. However, the wax-based material for mechanical cutting is not contained in any relevant research. To this end, we carry out research in this area.