The electrical properties of sulfur-implanted cubic boron nitride thin films

Cubic boron nitride （c-BN） thin films are deposited on p-type Si wafers using radio frequency （RF） sputtering and then doped by implanting S ions. Wile implantation energy of the ions is 19 keV, and the implantation dose is between 1015 ions/cm2 and 1016 ions/cm2. The doped c-BN thin films are then annealed at a temperature between 400℃ and 800℃. The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders, and the activation energy of c-BN thin films is 0.18 eV.

In situ infrared spectroscopic study of cubic boron nitride thin film delamination

This paper investigates the procedure of cubic boron nitride （cBN） thin film delamination by Fourier-transform infrared （IR） spectroscopy. It finds that the apparent IR absorption peak area near 1380cm^-1 and 1073 cm^-1 attributed to the B-N stretching vibration of sp2-bonded BN and the transverse optical phonon of cBN, respectively, increased up to 195% and 175% of the original peak area after film delamination induced compressive stress relaxation. The increase of IR absorption of sp2-bonded BN is found to be non-linear and hysteretic to film delamination, which suggests that the relaxation of the turbostratic BN （tBN） layer from the compressed condition is also hysteretic to film delamination. Moreover, cross-sectional transmission electron microscopic observations revealed that cBN film delamination is possible from near the aBN（amorphous BN）/tBN interface at least for films prepared by plasma-enhanced chemical vapour deposition.

Influence of oxygen on the growth of cubic boron nitride thin films by plasma-enhanced chemical vapour deposition

Cubic boron nitride thin films were deposited on silicon substrates by low-pressure inductively coupled plasmaenhanced chemical vapour deposition. It was found that the introduction of 02 into the deposition system suppresses both nucleation and growth of cubic boron nitride. At a B2H6 concentration of 2.5% during film deposition, the critical O2 concentration allowed for the nucleation of cubic boron nitride was found to be less than 1.4%, while that for the growth of cubic boron nitride was higher than 2.1%. Moreover, the infrared absorption peak observed at around 1230- 1280 cm^-1, frequently detected for cubic boron nitride films prepared using non-ultrahigh vacuum systems, appears to be due to the absorption of boron oxide, a contaminant formed as a result of the oxygen impurity. Therefore, the existence of trace oxygen contamination in boron nitride films can be evaluated qualitatively by this infrared absorption peak.

Tribological and anti-corrosion performance of epoxy resin composite coatings reinforced with differently sized cubic boron nitride(CBN)particles

A series of high solid content(30 wt%)epoxy resin(EP)composite coatings reinforced with differently sized cubic boron nitride(CBN)particles were fabricated successfully on 304 L stainless steel.Polydopamine(PDA)was used to improve the dispersibility of CBN particles in EP.The structural and morphological features of the CBN particles and the composite coatings were characterized by Raman spectroscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Moreover,a UMT-3 tribometer and surface profiler were used to investigate the tribological behaviors of the as-prepared composite coatings.Electrochemical impedance spectroscopy(EIS)and Tafel analysis were used to investigate the coatings'anti-corrosion performance.The results demonstrated that the CBN fillers could effectively enhance the tribological and anti-corrosion properties of the EP composite coatings.In addition,when the additive proportion of the microsized(5μm)and nanosized(550 nm)CBN particles was 1:1,the tribological property of the EP composite coatings was optimal for dry sliding,which was attributed to the load carrying capability of the microsized CBN particles and the toughening effect of the nanosized CBN particles.However,when the additive proportion of the microsized and nanosized CBN particles was 2:1,the tribology and corrosion resistance performance were optimal in seawater conditions.We ascribed this to the load-carrying capacity of the microparticles,which played a more important role under the seawater lubrication condition,and the more compact structure,which improved the electrolyte barrier ability for the composite coatings.

Detailing interfacial reaction layer products between cubic boron nitride and Cu-Sn-Ti active filler metal

In the present study,we offer an in-depth analysis over the microstructure,thickness and product composition of the interfacial reaction layer generated upon CBN/Cu-Sn-Ti active filler metal at 1223 K.Current findings demonstrate that adequate wettability and satisfactory bonding have been achieved via chemical reactions between Ti and N,B.More importantly,we report,for the first time,the formation of a three-layer juxtaposition of reaction products,namely,TiN,TiB2 and TiB,along the diffusion path of Ti.Meanwhile,we determine the average layer thickness to be 1.24 μm.Through deep etching,we unambiguously present morphologies of the newly formed TiN and TiB2,which are columnar and bulky,re spectively,and constitute the formation of a high strength metallu rgical interfacial bonding layer,and is crucial towards gaining enhanced grinding performance.Finally,we propose a possible reaction sequence and mechanism that govern the nucleation and growth of corre s ponding crystals.

In situ synthesis of polycrystalline cubic boron nitride in cBN-Al-Ti system with different Gd_(2)O_(3) additions

Polycrystalline cubic boron nitride was sintered under high temperature(1400℃)and high pressure(5.5 GPa)using an in situ synthesis method.The composition,microstructure,relative density and mechanical properties of the polycrystalline cubic boron nitride(PcBN)with different contents of Gd_(2)O_(3) were studied by means of X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy-dispersive spectroscopy(EDS).The results show that the phases of TiB_(2),TiN,AIN,AlTi_(2)N and GdB_(6) are formed through in situ synthesis of cBN-Al-Ti-Gd_(2)O_(3) system.With the Gd_(2)O_(3) content increasing,the relative density increases and mechanical properties of PcBN begin to increase and then decrease.Proper amount of Gd_(2)O_(3) can advance the formation of TiB_(2) and improve the aspect ratio of TiB_(2).When Gd_(2)O_(3) content is 1.0 wt%,the PcBN exhibits optimal comprehensive mechanical properties,with a microhardness of 33.35 GPa and a flexural strength of 972.37 MPa.

Growth kinetics of interfacial reaction layer products between cubic boron nitride and Cu-Sn-Ti active filler metal

In the present investigation,the growth kinetics of interfacial reaction layer products between cubic boron nitride(CBN) and Cu-Sn-Ti filler metal has been thoroughly investigated.Detailed morphological and compositional features of respective compounds have been demonstrated for a wide brazing temperature ranging from 1153 K to 1223 K.It is found that within 30 minutes brazing holding time,the reaction layer growth is largely determined by the population of Ti N via effective Ti diffusion with an activation energy of 223.51 k J/mol,leading to parabolic growth patterns.It is further revealed that TiN grows both in axial and length dimensions,which eventually extends to the forefront and covers the reaction layer.

Diamond/c-BN van der Waals heterostructure with modulated electronic structures

The structural and electronic properties of(100),(110), and(111) diamond/cubic boron nitride(c-BN) heterostructures are systematically investigated by first principles calculation. The interface between diamond and c-BN shows the weak van der Waals interactions, which is confirmed by the interface distance and interface binding energy. The diamond/cBN structures are the direct bandgap semiconductors with moderate bandgap values ranging from 0.647 e V to 2.948 e V.This work helps to promote the application of diamond in electronic and optoelectronic devices.

Cutting Temperature and Tool Wear of Hard Turning Hardened Bearing Steel

A study was undertaken to investigate the performan ce of PCBN tool in the finish turning GCr15 bearing steel with different hardness between 30～64 HRC. The natural thermocouple was used to measure the cutting tem p erature, tool life and cutting temperature were investigated and compared. The m aterial can be heated by this instrument which using low voltage and high elec trical current, while PCBN can’t be heated by electrifying directly, so the ke ntanium layer coating over the PCBN is heated, so the PCBN is heated and its th ermoelectric property is got by this method. [TPP129,+60mm88mm,Y,PZ#] Fig.1 Effect of cutting depth and workpiec hardness on. the cutting temperatureThe objective was to determine the influence of the workpiece hardness on change s in cutting temperature and tool wear characterize. It can be found from Fig.1 that the cutting temperature show an increasing tendency with the improvement of workpiece hardness within the cutting speed scope when the workpiece hardness i s under HRC50. And on the other hand, it is found that the cutting temperature s how the downtrend with the improvement of workpiece hardness when the workpiece hardness is over HRC50. According to experimental results, the critical hard ness when turning hardened GCr15 bearing steel with PCBN tool is about HRC50. Th e wear causes of PCBN tool have been found out through taking photos on the micr o-shape of PCBN poly-laminate initial surface as well as face and flank of wea r tool and analysis on chemical elements. It is discovered that the PCBN tools a re not suitable for cutting the workpiece at nearly critical hardness, because n ear the critical hardness, PCBN wear at the highest speed. For researching the w ear rule of PCBN tool, the tool wear experiments have been carried on by using b earing steel GCr15 at hardness HRC40 and HRC60 with changing cutting speed. The indexes of tool life equations is gained under two kinds of conditions w hich are bigger than 0.6, so the effects of cutting speed on the PCBN tool are m uch less than that of carbide tool and ceramic tool.

Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

The excellent physical and chemical properties of cubic boron nitride(c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon(100) substrates by radio frequency(RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of Hgas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed.

Preparation of Porous Ceramic Bond cBN Composites Using cBN Micro-particles as Additive

Ceramic bond cBN composites with large pores were prepared by firing at 740 ℃ for 1 h using Na2O -Al2O3-B2O3 -SiO2 gluss and cBN abrasives （particles size 0. 150 mm/0. 124 mm） as main starting materials, eBN micro-particles （particles size O. 014 mm ） as the additive, and NH4HCO3 as the pore forming agent. The effect of NH4HCO3 and cBN micro-particles on the microstructure and properties of cBN composites was studied. The results show that for the cBN composite without cBN micro-particles the porosity obviously increases when the NH4HCO3 addition increases from 0 to 21 mass% , and increases slightly when the NH4HCO, addition increuses from 28 muss% to 42 muss% ; and the bending strength decreases with the NH4HCO3 addition increasing. For the cBN composite with 14 mass% cBN micro- particles, the porosity increases continuously with the NH4HCO3 addition increasing, achieving 56. 14% for the NH4HCO3 addition of 42 mass% , while, an obvious decrease of the bending strength is obtained. It is clearly indicated that the cBN micro-particles contribute to the high porosity and high strength of the porous ceram, ic bond cBN composites.

Brazed joints of CBN grains and AISI 1045 steel with AgCuTi-TiC mixed powder as filler materials

The brazing process of cubic boron nitride （CBN） grains and AISI 1045 steel with AgCuTi-TiC mixed powder as a filler material was carried out.The joining strength and the interfacial microstructure were investigated.The experimental results indicate that the spreading of the molten filler material on AISI 1045 steel is decreased with the increase of TiC content.A good interface is formed between the TiC particulates and AgCuTi alloy through the wetting behavior.In the case of AgCuTi＋16wt% TiC,the strength of the brazed steel-to-steel joints reached the highest value of 95MPa dependent upon the reinforcement effect of TiC particles within the filler layer.Brazing resultants of TiB2,TiB,and TiN are produced at the interface of the CBN grains and the AgCuTi-TiC filler layer by virtue of the interdiffusion of B,N,and Ti atoms.

Hydrochloric Acid-Promoted Synthesis of cBN via Hydrothermal Route

Single phase crystalline cubic boron nitride （cBN） with high yield was prepared by hydrothermal route at low temperature, using hydrochloric acid （HCI） as the promoter. The promotion effect of HCI on the synthesis of cBN is briefly discussed.

DEPOSITION OF c-BN FILMS AND ADHESION IMPROVEMENT

Cubic boron nitride (c-BN) films were successfully grown on Si(100)substrates by a helicon wave plasma-assisted chemical vapor deposition technique.The lower limits of rf substrated bias voltage and plasma density for formation of a single phase c-BN film were 350V and 4.5×10￣(10) cm￣(3),respectively. The grown c-BN films demonstrated a poor adhesion to the substrates. A postannealing treatment at 800℃ C in N_2 atmosphere was found very effective in relieving the compressive stress in the films which were thereby stabilized to improve the adhesion.

XRD Doping Control of Light-Emitting cBN with a Large Size Mismatch between the Dopant and Intrinsic Atoms

Cubic boron nitride (cBN) as the outstanding representative of the family of semiconducting wide bandgap nitrides and the closest analogue of diamond, is produced and investigated. XRD as method for doping control of cBN with impurities of large atomic sizes, is suggested. The larger an atomic size mismatch between doping and intrinsic atoms of a semiconductor’s crystal lattice, the stronger its response through own strains and distortions. The distortions are expected to be notable in the case of the smallest intrinsic atoms of cBN and diamond. The light-emitting cBN doped with various rare-earth elements (RE) in different concentrations under high pressure conditions is synthesized in form of the cBN: RE single phase micropowders. The micro-powders showed the discrete photoluminescence spectra in IR-, red and green spectral ranges which were attributed to the intra-electronic transitions of RE3+ ions located in cBN crystal lattice. The locations of the RE3+ ions in cBN crystal lattice are discussed. The data of XRD (CuKα) analysis of the cBN:RE micropowders are repre- sented. Extra-splits (as the additional ones to the α1-α2-splits on CuKα) of the cBN parent peaks in XRD patterns of the cBN: RE, are discovered and analyzed using appropriate computer programs. As established, crystal lattice of cBN due to the incorporation of RE3+ ions, represents a disordered solid solutions which are nonuniformly distorted in dependence on the ions’ size and their concentrations in cBN. Results of the present work can be useful to manufacture cBN with predictable functional properties, as well as for in situ doping control of cBN and diamond.

CBN grain wear and its effects on material removal during grinding of FGH96 powder metallurgy superalloy

Grinding with cubic boron nitride(CBN)superabrasive is a widely used method of machining superalloy in aerospace industries.However,there are some issues,such as poor grinding quality and severe tool wear,in grinding of powder metallurgy superalloy FGH96.In addition,abrasive wheel wear is the significant factor that hinders the further application of CBN abrasive wheels.In this case,the experiment of grinding FGH96 with single CBN abrasive grain using different parameters was carried out.The wear characteristics of CBN abrasive grain were analyzed by experiment and simulation.The material removal behavior affected by CBN abrasive wear was also studied by discussing the pile-up ratio during grinding process.It shows that morphological characteristics of CBN abrasive grain and grinding infeed direction affect the CBN abrasive wear seriously by simulation analysis.Attrition wear,micro break,and macro fracture had an important impact on material removal characteristics.Besides,compared with the single cutting edge,higher pile-up ratio was obtained by multiple cutting edges,which reduced the removal efficiency of the material.Therefore,weakening multiple cutting edge grinding on abrasive grains in the industrial production,such as applying suitable dressing strategy,is an available method to improve the grinding quality and efficiency.

Review on monolayer CBN superabrasive wheels for grinding metallic materials

A state-of-the-art review on monolayer electroplated and brazed cubic boron nitride（CBN） superabrasive wheels for grinding metallic materials has been provided in this article. The fabrication techniques and mechanisms of the monolayer CBN wheels are discussed. Grain distribution, wheel dressing, wear behavior, and wheel performance are analyzed in detail. Sample applications of monolayer CBN wheel for grinding steels, titanium alloys, and nickel-based superalloys are also provided. Finally, this article highlights opportunities for further investigation of monolayer CBN grinding wheels.

Grinding performance evaluation of porous composite-bonded CBN wheels for Inconel 718

For high-efficiency grinding of difficult-to-cut materials such as titanium and nickel alloys, a high porosity is expected and also a sufficient mechanical strength to satisfy the function.However, the porosity increase is a disadvantage to the mechanical strength. As a promising pore forming agent, alumina bubbles are firstly induced into the abrasive layer to fabricate porous cubic boron nitride（CBN） wheels. When the wheel porosity reaches 45%, the bending strength is still high up to 50 MPa with modified orderly pore distribution. A porous CBN wheel was fabricated with a total porosity around 30%. The grinding performance of the porous composite-bonded CBN wheel was evaluated in terms of specific force, specific grinding energy, and grinding temperature, which were better than those of the vitrified one under the same grinding conditions. Compared to the vitrified CBN wheel, clear straight cutting grooves and less chip adhesion are observed on the ground surface and there is also no extensive loading on the wheel surface after grinding.

Processing and properties of PcBN composites fabricated by HPHT using PSN and Al as sintering additive

Dense polycrystalline cubic boron nitride(PcBN)composites were fabricated by high-pressure and high-temperature(HPHT)sintering using polysilazane(PSN)and Al as sintering additive.After high-energy ball milling,the cBN fine particles were uniformly coated with PSN by ultrasonic treatment.After thermocuring and pyrolysis,the cBN–SiCN particles were mixed with Al The PcBN composites were prepared after sintering a1450°C for 10 min with a pressure of 5 GPa.The refining effect of high-energy ball milling on the c BN particles was studied by scanning electron microscopy(SEM)and laser particle size analyzer.The oxidation of the cBN particles after milling was investigated by nitrogen–oxygen analyzer.The phase composition and microstructure of the sintered PcBN composites were investigated by X-ray diffractometer(XRD)and SEM.The main phases of the sintered PcBN composites are c BN,AlN,SiC and Si3N4The conversion of cBN to hBN was inhibited by the formation of AlN.The mechanical properties of the sintered PcBN composites were improved by the appearance of SiC and Si3N4.The density and mechanical properties of the PcBN composites both increased with the content of the cBN particles increasing.The sintered sample with 60 wt%cBN,30 wt%PSN and 10 wt%Al showed the best results density of 99.7%,Vickers’hardness of(25.2±0.8)GPa and flexural strength of(602±15)MPa.

Influence of binder systems on sintering characteristics, microstructures, and mechanical properties of PcBN composites fabricated by SPS

Cubic boron nitride(cBN)with high hardness,thermal conductivity,wear resistance,and chemical inertness has become the most promising abrasive and machining material.Due to the difficulty of fabricating pure cBN body,generally,some binders are incorporated among cBN particles to prepare polycrystalline cubic boron nitride(PcBN).Hence,the binders play a critical factor to the performances of PcBN composites.In this study,the PcBN composites with three binder systems containing ceramic and metal phases were fabricated by spark plasma sintering(SPS)from 1400 to 1700℃.The sintering behaviors and mechanical properties of the composites were investigated.Results show that the effect of binder formulas on mechanical properties mainly related to the compactness,mechanical performances,and thermal expansion coefficient of binder phases,which affect the carrying capacity of the composites and the bonding strength between binder phases and cBN particles.The PcBN composite with SiAlON phase as binder presented optimal flexural strength(465±29 MPa)and fracture toughness(5.62±0.37 MPa·m^(1/2)),attributing to the synergistic effect similar to transgranular and intergranular fractures.Meanwhile,the excellent mechanical properties can be maintained a comparable level when the temperature even rises to 800℃.Due to the weak bonding strength and high porosity,the PcBN composites with Al_(2)O_(3)–ZrO_(2)(3Y)and Al–Ti binder systems exhibited inferior mechanical properties.The possible mechanisms to explain these results were also analyzed.