CrTiAlN复合涂层硬质合金刀具的制备与切削性能研究

利用多弧离子镀技术在YT14硬质合金刀具上制备了CrTiAIN复合涂层,对不同偏压条件下CrTiAIN复合膜的表面形貌、硬度、结合性能进行了系统研究,采用X射线衍射分析技术(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)等现代材料分析技术对CrTiAIN复合涂层的微观组织结构进行了分析表征,结果表明:CrTiAIN复合涂层的主要成分为Cr、Ti、Al、N、O,相组成为Cr、CrN、Cr2N和TuN晶体相与AIN非晶相.在干式切削条件下,不同涂层刀具的切削寿命的排序依次为:CrrnAlNTiAINTiN未涂层,同时对不同涂层刀具的耐磨损特性进行了讨论分析.     

Investigation of structure and mechanical properties of plasma vapor deposited nanocomposite TiBN films

TiBN coatings have huge potential applications as they have excellent properties with increasing modern industrial requirements.Nanocomposite TiBN coatings were synthesized on cemented carbide,high speed steel and Si substrates by using cathodic arc plasma ion plating from pure TiB_2 ceramic targets.The structure and mechanical properties of the TiBN coatings were significantly influenced by the nitrogen partial pressure.Rutherford backscattering spectrometry demonstrates that the nitrogen content of the coating varied from 2.8%to 34.5%and highresolution electron microscopy images reveal that all coatings have the characteristic of nanocrystals embedded in an amorphous matrix.The root-mean-square roughness of the coatings increases from 3.73 to 14.64 nm and the coefficients of friction of the coatings at room temperature vary from 0.54 to 0.73 with increasing nitrogen partial pressure.The microhardness of the coating increases up to 35.7 GPa at 10 seem N_2 flow rate.The smallest wear rate is2.65×10~(-15)m~3 N~(-1)m~(-1)which indicates that TiBN coatings have excellent wear resistance.The adhesion test revealed that the TiBN coatings have good adhesion at low nitrogen partial pressure.     

脉冲偏压对贫铀表面磁控溅射离子镀铝结合强度的影响

采用磁控溅射离子镀技术在不同偏压下于贫铀表面制备铝镀层，用扫描电镜和俄歇电子能谱仪对镀层形貌和界面元素分布进行分析，用拉伸法对镀层的结合强度进行测定。结果表明：在-900V脉冲偏压下所得镀层与铀基体结合良好，镀层与基体之间存在较为明显的“伪扩散区”；与直流偏压相比较，脉冲偏压所得镀层结合强度明显增强，镀层的致密性显著改善。     

Surface morphology influence on deuterium retention in beryllium films prepared by thermionic vacuum arc method

In a plasma-confinement device, material eroded from plasma facing components will be transported and re-deposited at other locations inside the reaction chamber. Since beryllium from the first wall of the ITER fusion reactor will be eroded, ionized in the scrape-off layer plasma and finally re-deposited on divertor surfaces flowing along the magnetic field, it is important to study the properties of divertor armour materials (C, W) coated with beryllium.By applying different bias voltages (−200 V to +700 V) to the substrates during deposition, the morphology of the obtained films was modified. The films’ morphology was characterized by means of AFM and SEM, and it was found that the coatings prepared using negative bias voltage at the substrate during deposition are more compact and have a smoother surface compared to the samples prepared with positive bias voltage. The thickness and composition of each film were measured using Rutherford backscattering spectrometry (RBS). A study of deuterium implantation and retention into the prepared films was performed at IPP Garching in the high current ion source.     

Experimental Study of the Influence of Process Pressure and Gas Composition on GaAs Etching Characteristics in Cl2/BCl3-Based Inductively Coupled Plasma

A study of Cl2/BCl3-based inductively coupled plasma (ICP) was conducted using thick photoresist mask for anisotropic etching of 50 μm diameter holes in a GaAs wafer at a relatively high average etching rate for etching depths of more than 150 μm. Plasma etch characteristics with ICP process pressure and the percentage of BCl3 were studied in greater detail at a constant ICP coil/bias power. The measured peak-to-peak voltage as a function of pressure was used to estimate the minimum energy of the ions bombarding the substrate. The process pressure was found to have a substantial influence on the energy of heavy ions. Various ion species in plasma showed minimum energy variation from 1.85 to 7.5 eV in the pressure range of 20 to 50 mTorr. The effect of pressure and the percentage of BCl3 on the etching rate and surface smoothness of the bottom surface of the etched hole were studied for a fixed total flow rate. The etching rate was found to decrease with the percentage of BCl3, whereas the addition of BCl3 resulted in anisotropic holes with a smooth veil free bottom surface at a pressure of 30 mTorr and 42% BCl3. In addition, variation of the etching yield with pressure and etching depth were also investigated.     

Effect of radio-frequency substrate bias on ion properties and sputtering behavior of 2 MHz magnetron sputtering

The effect of radio-frequency substrate bias on ion properties and sputtering behavior of 2 MHz magnetron discharge was investigated. The ion velocity distribution function(IVDF), the maximum ion energy and ion flux density were measured at the substrate by a retarding field energy analyzer. The sputtering behavior was investigated by the electric characteristics of target and bias discharges using voltage–current probe technique. It was found that the substrate bias led to the decrease of sputtering power, voltage and current with the amplitude 7.5%. The substrate bias also led to the broadening of IVDFs and the increase of ion flux density, made the energy divergent of ions impacting the substrate. This effect was further enhanced by increasing bias power and reducing discharge pressure.     

Influences of frequency on nitrogen fixation of dielectric barrier discharge in air

The influences of frequency on nitrogen fixation of dielectric barrier discharge in air were studied by electrical diagnostics, gas detection and infrared detection methods. The system power, nitrogen oxide concentration, voltage–current waveform, dielectric surface temperature distribution and filamentous discharge pictures were measured, and then the energy yield was calculated; paper studied their changing tendencies in the presence of frequency. Results show that frequency has strong influences on nitrogen fixation. When the parameters of reaction chamber and amplitude of applied voltage is fixed, with the increasing of frequency, the system power increases; in 5-10 kHz, nitrogen oxide gas concentration up to 1113.7 mg m~(-3), and 7 k Hz is the optimal nitrogen fixation frequency whose energy yield is 20.5 mg(m~3 W)~(-1).     

国产VDMOS电离辐射环境中的敏感参数研究

分析了国产VDMOS(Vertical Double-diffusion MOSFET)总剂量试验数据,并比较了辐照环境中不同偏置下电学参数的变化差异,发现新工艺研制的VDMOS器件辐照敏感参数为击穿电压和阈值电压.根据试验结果得到考核VDMOS辐照可靠性的有效试验方法:击穿电压抗辐照考核时应采用漏偏置,阈值电压抗辐照考核时应采用栅偏置.     

双面硅条探测器的研制与测试

研制了双面硅条探测器。探测器灵敏面积为48mm×48mm,厚约300μm,结面和欧姆面的硅条互相垂直,均由相互平行、宽度相等的48条组成,每条宽0.9mm、间距0.1mm。对其电气特性(耗尽偏压、反向漏电流、条间电阻)和探测特性(上升时间、能量分辨、条间串扰)进行了测试。在偏压为-15V时,各条平均反向漏电流小于10nA。对于从结面入射的5.157 MeV的α粒子,前放信号上升时间约45ns,结面各条的能量分辨率约0.6%~0.7%,基本无条间串扰;欧姆面各条能量分辨率较差,存在条间串扰。     

Discharge Modes Suggested by Emission Spectra of Nitrogen Dielectric Barrier Discharge with Wire-Cylinder Electrodes

In this paper,nitrogen dielectric barrier discharge(DBD) plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure.By varying the nitrogen gas flow(FN) in the range of 0-1 m3/h,the plasma optical emission spectra(OES) were measured and studied.The vibration(T_(vib)) and rotation temperature(T_(rot)) of nitrogen were obtained,by fitting the rovibronic bands of N_2(C~3∏_u-B~3∏_g,0-1),and by the Boltzmann plot method for purposes of comparison.T_(vib) increased up to 2481 K with increasing nitrogen flow till0.2 m3/h,and then decreased with further increasing FN,while Trot decreased monotonously and approached to-350 K for FN ≥ 0.6 m~3/h.The intensity of N_2(C~3∏_u-B~3∏_g,0-0,1-0,0-3) and N_2~+(B~2∑_u~+-X~2Σ_g~+,0-0) exhibited similar evolution with increasing FN to those of the T_(vib) and Trot,respectively.The discharge photos revealed that the discharge filaments gradually decreased with increasing FN,and eventually disappeared,which implied that a discharge mode transition emerged with increasing FN.The possible mechanism for the discharge mode transition is studied in detail according to the vibration(T_(vib)) and rotation temperature(T_(rot)) of nitrogen.     

Experimental Study of Electron Emission Characteristics of a Surface Flashover Trigger in a Low Pressure Environment

Characteristics of electron emission induced by a surface flashover trigger device in a low-pressure trigger switch were investigated. A test method to measure the emitted charges from the trigger device was developed, and the factors affecting the emitted charges were analyzed. The results indicated that the major emitted charges from the trigger device were induced by surface plasma generated by surface flashover occurring on the trigger dielectric material. The emitted charges and the peak emission current increased linearly with the change in the trigger voltage and bias voltage. The emitted charges collected from the anode were affected by the gap distance. However, the emitted charges were less affected by the anode diameter. Furthermore, the emitted charges and the peak emission current decreased rapidly with the increase in gas pressure in a range from 0 to 100 Pa, and then remained stable or changed slightly when the increase in gas pressure up to 2400 Pa.     

射频等离子体法在单晶硅衬底上形成的非晶碳膜及其性质

由离子和离子束技术形成的非晶碳膜具有良好的电绝缘性、对红外及可见光透明、硬度大、耐腐蚀等优良性质,可望在半导体器件、激光器件、太阳电池和材料保护等方面得到应用而受到重视。近年来很多作者先后报道了用未经质量分析的低能碳离子束直接沉积、离子束溅射沉积、离子镀、射频辉光放电离化碳氢化合物的等离子体沉积、经质量分析的低能碳离子束沉积等方法在单晶硅、玻璃、不锈钢等不同衬底上形成非晶碳膜的结果。碳膜的物理性质与沉积条件有密切关系,根据物理性质非晶碳膜大致可以分为三类,即导电、不透明的类石墨膜;绝缘、透明、质软的类聚合物膜;透明、绝缘、硬度大的类金刚石膜。     

The Effect of Applied Voltage and Operating Pressure on Emitted X-Ray from Nitrogen (N<Subscript>2</Subscript>) Gas in APF Plasma Focus Device

In the present work, the effect of applied voltage and operating pressure on behaviour of X-rays emitted from nitrogen gas (N₂) used in APF plasma focus facility is investigated. It was found that the optimum conditions for high emissions of SXR and HXR from the plasma focus (PF) are different. At four applied voltages of 10, 11, 12, and 13 kV, the optimum pressures for SXR and HXR emissions of nitrogen gas (N₂) were obtained. At lower voltages, 10, and 11 kV optimum pressure for SXR emission was 3.5 torr while for HXR emission was 2.5 torr. At higher voltages, 12, and 13 kV, the optimum pressures shift to higher values at 4 and 3 torr for SXR and HXR emissions, respectively. Among the applied voltages, the least intensity of both SXR and HXR was at voltage 10 kV and the most intensity was for 13 kV which confirm with increasing voltage, the intensity of X-ray emission increases. Also the results obtained by images of pin-hole camera were in compatible with the results of detected signals by different filtered Pin-diodes and Scintillation detector. Our results illustrate that the voltage and the pressure are effective parameters in X-ray emission from the PF.     

共面栅碲锌镉探测器读出电路设计及性能研究

为有效读出共面栅碲锌镉(CPG-CZT)探测器的核脉冲信号,本文结合CPG-CZT探测器工作原理及国内外研究,设计了可用于CPG-CZT探测器的读出电路,主要包括高压偏置电路、前置放大电路、增益调节及减法电路。为研究读出电路性能,本文测试了各单元电路的性能及探测系统能量分辨率随偏置电压、增益调节电路中两路信号的相对增益G的变化规律。结果表明：高压偏置电路两路输出偏压与输入偏置电压的相关系数R²均为0.998;前置放大电路输出噪声为5 mV;增益调节及减法电路输出信号噪声为10 mV;输入偏置电压、相对增益G的变化均会影响探测系统能量分辨率,当偏置电压为-1650 V、相对增益G为0.7时对¹³⁷Cs源产生的γ射线能量分辨率最佳,可达3.65%,且无明显拖尾现象。     

An Experimental Study on Atmospheric Pressure Glow Discharge in Different Gases

Usually,the electrical breakdown of dielectric barrier discharge(DBD) at atmospheric pressure leads to a filamentary non-homogeneous discharge,However,it is also possible to obtain a diffuse DBD in homogeneous form,called atmospheric pressure glow discharge(APGD).We obtained a uniform APGD in helium and in the mixture of argon with alcohol,and studied the electrical characteristics of helium APGD.It if found that the relationship between discharge current and source frequency is different depending on the difference in gas gap when the applied voltage is kept constant.The discharge current shows an increasing trend with the increased frequency when gas gap is 0.8cm ,but the discharge current tends to decrease with the increased frequency when the gas gap increases.The discharge current always increases with the increased applied voltage when the source frequency is kept constant.We also observed a glow-like discharge in nitrogen at atmospheric pressure.     

Mechanical Properties and Uniformity of Nanocrystalline Diamond Coating Deposited Around a Sphere by MPCVD

Nanocrystalline diamond coatings were deposited by MPCVD on the spheres used for a ball bearing.The nanocrystalline coatings with a grain size of 50 nm were confirmed by the surface morphology and composition analysis.The hardness of the coating is 20-40 GPa tested by nanoindentation,which is higher than that of tungsten carbide and silicon nitride substrates.The coating around the sphere observed from the Micro CT images is uniform with a thickness of12 μm.     

The Effect of Working Gas Admixture,Applied Voltage and Pressure on Focusing Time Parameter in the APF Plasma Focus Device

In the present research the effects of key parameters, applied voltage, working gas composition and pressure, on the focusing time in the APF plasma focus device are investigated. Pure nitrogen (N₂) and three volumetric ratios (90:10), (75:25), and (50:50) of (N₂:Ne) admixture gases were used as the filling gas in a range of four applied voltage between 10 and 13 kV and seven operating pressure of 1.5–4.5 torr. It was found that with addition of 1 kV in the charging voltage, a decrease of around 50–75 ns happens in the focusing time while with increase of 0.5 torr in operating pressure, an increment of around 100–150 ns occurs in the focusing time. Also it was observed that the focusing time decreases around 50–75 ns with addition of 10% neon (Ne) in volumetric ratio of admixture working gas at all applied voltage and operating pressure.     

CVD金刚石膜X射线探测器的研制及性能研究

金刚石以其独特的性能成为辐射探测器的理想材料.采用HFCVD方法制备了高质量、(100)取向的CVD金刚石膜,在此基础上研制出X射线探测器.使用55Fe 5.9keV X射线研究了CVD金刚石膜探测器的光电流和电荷收集效率.结果表明,探测器在偏压加到100V还具有好的欧姆接触;电场为50kV·cm-1时的暗电流与光电流分别为16.3和16.8nA;电荷收集效率η为45.1%,对应的电荷收集距离δ(CCD)为9.0μm.     

Anomalous acceleration of ions in a plasma accelerator with an anodic layer

In a plasma accelerator with an anodic layer(PAAL), we discovered experimentally the effect of‘super-acceleration' of the bulk of the ions to energies W exceeding the energy equivalent to the discharge voltage Vd. The E?×?B discharge was ignited in an environment of atomic argon and helium and molecular nitrogen. Singly charged argon ions were accelerated most effectively in the case of the largest discharge currents and pressure P of the working gas. Helium ions with W??eV_d(e being the electron charge) were only recorded at maximum pressures. Molecular nitrogen was not accelerated to energies W??e Vd. Anomalous acceleration is realized in the range of radial magnetic fields on the anode 2.8?×?10~(–2)≤B_(rA)≤4?×?10~(–2) T. It was also found analytically that the cathode of the accelerator can receive anomalously accelerated ions. In this case, the value of the potential in the anodic layer becomes higher than the anode potential, and the anode current exceeds some critical value. Numerical modeling in terms of the developed theory showed qualitative agreement between modeling data and measurements.     

Discharge characteristics of a needle-toplate electrode at a micro-scale gap

To understand the discharge characteristics under a gap of micrometers,the breakdown voltage and current–voltage curve are measured experimentally in a needle-to-plate electrode at a microscale gap of 3–50 μm in air.The effect of the needle radius and the gas pressure on the discharge characteristics are tested.The results show that when the gap is larger than 10 μm,the relation between the breakdown voltage and the gap looks like the Paschen curve;while below 10 μm,the breakdown voltage is nearly constant in the range of the tested gap.However,at the same gap distance,the breakdown voltage is still affected by the pressure and shows a trend similar to Paschen's law.The current–voltage characteristic in all the gaps is similar and follows the trend of a typical Townsend-to-glow discharge.A simple model is used to explain the non-normality of breakdown in the micro-gaps.The Townsend mechanism is suggested to control the breakdown process in this configuration before the gap reduces much smaller in air.