Deposition of Diamond-Like Carbon on Inner Surface by Hollow Cathode Discharge

A cylindrical hollow cathode discharge （HCD） in CH4/Ar gas mixture at pressure of 20-30 Pa was used to deposit diamond-like carbon （DLC） films on the inner surface of a stainless steel tube. The characteristics of the HCD including the voltage-current curves, the plasma im- ages and the optical emission spectrum （OES） were measured in Ar and CHn/Ar mixtures. The properties of DLC films prepared under different conditions were analyzed by means of Raman spectroscopy and scanning electron microscopy （SEM）. The results show that the electron exci- tation temperature of HCD plasma is about 2400 K. DLC films can be deposited on the inner surface of tubes. The ratio of sp3/sp2 bonds decreases with the applied voltage and the deposition time. The optimizing CH4 content was found to be around CH4/Ar =1/5 for good quality of DLC films in the present system.

Improvement of plasma uniformity and mechanical properties of Cr films deposited on the inner surface of a tube by an auxiliary anode near the tube tail

In order to improve the length of plasma in a whole tube and mechanical properties of Cr films deposited on the inner surface of the tube, a high-power impulse magnetron sputtering coating method with a planar cathode target and auxiliary anode was proposed. The auxiliary anode was placed near the tube tail to attract plasma into the inner part of the tube. Cr films were deposited on the inner wall of a 20# carbon steel tube with a diameter of 40 mm and length of 120 mm. The influence of auxiliary anode voltage on the discharge characteristics of the Cr target, and the structure and mechanical properties of Cr films deposited on the inner surface of the tube were explored. With higher auxiliary anode voltage, an increase in substrate current was observed, especially in the tube tail. The thickness uniformity, compactness, hardness and H/E ratios of the Cr films deposited on the inner surface of the tube increased with the increase in auxiliary anode voltage. The Cr films deposited with auxiliary anode voltage of 60 V exhibited the highest hardness of 9.6 GPa and the lowest friction coefficient of 0.68.

Measurement of inner surface roughness of capillary by an x-ray reflectivity method

The inner surface roughness of a capillary is investigated by the reflectivity of x-rays penetrating through the capillary. The results are consistent with the data from atomic force microscope （AFM）. The roughness measured by this new method can reach the order of angstroms with high quality capillaries.

Experimental Investigation on the Bush Inner Surface Temperature of a High Speed Spiral Oil Wedge Sleeve Bearing

The temperature of bush inner surface temperature is measured by using infrared thermometer and transparent bearing,and temperature rise is measured by using thermocouple. The influence of rotating speed and axial location on the bush inner surface temperature is studied,and the influence of supply pressure and rotating speed on the temperature rise is analyzed. The results show the bush inner surface temperature and temperature rise of spiral oil wedge hydrodynamic bearing increase with the increase of rotation speed. In axial direction,the temperature is higher around the oil return hole. The temperature rise decreases with the increase of supply pressure. The highest temperature of bush inner surface and temperature rise are higher at higher speed,so the temperature rise is the fundamental reason which restricts the increase of rotation speed for high speed sleeve bearing.

Double Temperature and Density Phenomenon in Grid Enhanced Plasma Source Ion Implantation for Inner Surface Modification of Tubes

Inner surface coating for tubular samples was realized by the grid enhanced plasma source ion implantation （GEPSII） method. In the GEPSII system, two electrodes, a central rod electrode and a coaxial grid electrode were coaxially assembled inside the tube. Plasma was generated between the electrodes by a radio-frequency （RF） oscillating power source. Plasma then diffused through the grid and realized inner surface ion implantation by a negative high voltage applied to the tube. The plasma was then divided, by the grid, into two regions, namely the source plasma region and the diffused plasma region. The plasma＇s self-bias between two RF power source electrodes was measured. At the same time, the electron temperature and plasma density in the GEPSII system were measured by a scattering spectrometer. Results showed that the plasma properties of the two regions were entirely different; the plasma self-bias, which might greatly affect the sputtering rate of the central titanium electrode, depended on the electrode structure, gas pressure and RF power.

Modeling of Inner Surface Modification of a Cylindrical Tube by Plasma-Based Low-Energy Ion Implantation

The inner surface modification process by plasma-based low-energy ion implantation（PBLEII）with an electron cyclotron resonance（ECR）microwave plasma source located at the central axis of a cylindrical tube is modeled to optimize the low-energy ion implantation parameters for industrial applications.In this paper,a magnetized plasma diffusion fluid model has been established to describe the plasma nonuniformity caused by plasma diffusion under an axial magnetic field during the pulse-off time of low pulsed negative bias.Using this plasma density distribution as the initial condition,a sheath collisional fluid model is built up to describe the sheath evolution and ion implantation during the pulse-on time.The plasma nonuniformity at the end of the pulse-off time is more apparent along the radial direction compared with that in the axial direction due to the geometry of the linear plasma source in the center and the difference between perpendicular and parallel plasma diffusion coefficients with respect to the magnetic field.The normalized nitrogen plasma densities on the inner and outer surfaces of the tube are observed to be about 0.39 and 0.24,respectively,of which the value is 1 at the central plasma source.After a 5μs pulse-on time,in the area less than 2 cm from the end of the tube,the nitrogen ion implantation energy decreases from 1.5 keV to 1.3 keV and the ion implantation angle increases from several degrees to more than 40°;both variations reduce the nitrogen ion implantation depth.However,the nitrogen ion implantation dose peaks of about 2×10^（10）-7×10^（10）ions/cm^2 in this area are 2-4 times higher than that of 1.18×10^（10）ions/cm^2 and 1.63×10^（10）ions/cm^2 on the inner and outer surfaces of the tube.The sufficient ion implantation dose ensures an acceptable modification effect near the end of the tube under the low energy and large angle conditions for nitrogen ion implantation,because the modification effect is mainly determined by the ion implantation dose,just as the mass transfer process in PBLEII is dominated by low-energy ion implantation and thermal diffusion.Therefore,a comparatively uniform surface modification by the low-energy nitrogen ion implantation is achieved along the cylindrical tube on both the inner and outer surfaces.

Effects of deposition parameters on HFCVD diamond films growth on inner hole surfaces of WC-Co substrates

Deposition parameters that have great influences on hot filament chemical vapor deposition (HFCVD) diamond films growth on inner hole surfaces of WC?Co substrates mainly include the substrate temperature (t), carbon content (φ), total pressure (p) and total mass flow (F). Taguchi method was used for the experimental design in order to study the combined effects of the four parameters on the properties of as-deposited diamond films. A new figure-of-merit (FOM) was defined to assess their comprehensive performance. It is clarified thatt,φandp all have significant and complicated effects on the performance of the diamond film and the FOM, which also present some differences as compared with the previous studies on CVD diamond films growth on plane or external surfaces. Aiming to deposit HFCVD diamond films with the best comprehensive performance, the key deposition parameters were finally optimized as:t=830 °C,φ=4.5%,p=4000 Pa,F=800 mL/min.

Electrochemical micromachining of micro-dimple arrays on cylindrical inner surfaces using a dry-film photoresist

The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 lm in diameter and 22.7 lm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its potential low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.

Strain gradient induced grain refinement far below the size limit in a low carbon hypoeutectoid steel(0.19 wt%C)via pipe inner surface grinding treatment

A low carbon hypoeutectoid steel(0.19 wt%C)with proeutectoid ferrite and pearlite dual-components was subjected to surface plastic deformation via pipe inner surface grinding(PISG)at room temperature.The deformation microstructures for each component were systematically characterized along depth,and the patterns of structural evolution toward nanometer regime as well as the governing parameters were addressed.Proeutectoid ferrite grains were refined down to 17 nm,and the pattern covering a length scale of 4–5 orders of magnitude from micron-to nanometer-scale follows:formation of cellular dislocation structure(CDS),elongated dislocation structure(EDS),ultrafine lamellar structure(UFL)and finally the nanolaminated structure(NL).The pearlite experiences the deformation and refinement,and finally the transforming the ultrafine pearlite(UFP)into nanolaminated pearlite(NLP)with the ferrite lamellae as thin as 20 nm.Refinement for both UFL(UFP)and NL(NLP)can be realized via forming novel extended boundaries within ferrite lamellae.A critical lattice curvature of~2.8°is required for forming such extended boundary,corresponding to a minimum strain gradient of 0.25μm^(-1)for a 100 nm-thick lamella.Refinement below size limit(expressed by lamellar thickness d_Tin nm)is correlated with the strain gradient(χ,inμm^(-1))by:d_T=12.5/x.Refinement contributions from strain gradient caused by PISG processing and material heterogeneity were discussed.

In vivo and in vitro biomineralization in the presence of the inner-shell film of pearl oyster

The inner shell surface is the biomineralization site in shell formation and an inner-shell film covers it. This surface is composed of two regions： an outer calcitic region and an inner aragonitic region. In this study, some amalgamated calcite crystals were found in the calcitic region and some aragonitic ＂imprints＂ were found in the central part of the aragonitic region. The ＂imprints＂ are probably the trace of mantle cells that adhered to the inner shell surface when the shell was produced. Furthermore, to build a novel in vitro biomineralization system, the inner-shell film was detached from the shell and introduced to the calcitic crystallization solution. Crystallization experiments showed that nacre proteins could induce aragonite crystals in the novel system but inhibited calcite growth in the absence of the inner-shell film. These data suggested that the inner-shell film may induce aragonite growth in vivo by combining nacre proteins.

Uniformity of Plasma Density and Film Thickness of Coatings Deposited Inside a Cylindrical Tribe by Radio Frequency Sputtering

Plasma surface modification of the inner wall of a slender tube is quite difficult to achieve using conventional means. In the work described here, an inner coaxial radio frequency （RF） copper electrode is utilized to produce the plasma and also acts as the sputtered target to deposit copper films in a tube. The influence of RF power, gas pressure, and bias voltage on the distribution of plasma density and the uniformity of film thickness is investigated. The experimental results show that the plasma density is higher at the two ends and lower in the middle of the tube. A higher RF power and pressure as well as larger tube bias lead to a higher plasma density. Changes in the discharge parameter only affect the plasma density uniformity slightly. The variation in the film thickness is consistent with that of the plasma density along the tube axis for different RF power and pressure. Although the plasma density increases with higher tube biases, there is an optimal bias to obtain the highest deposition rate. It can be attributed to the reduction in self-sputtering of the copper electrode and re-sputtering effects of the deposited film at higher tube biases.

TWO-DIMENSIONAL NUMERICAL ANALYSIS OF PLASMA IMMERSION ION IMPLANTATION OF CYLINDRICAL BORES

Plasma immersion ion implantation (PIII), unrestricted by sight-light process, is considered a proper method for inner surface strengthening. Two-dimensional simulation oj inner surface PIII process of cylindrical bores were carried out in this paper using cold plasma fluid model, and influence of the bore's dimension on impact energy, retained dose and uniformity of inner surface were investigated.

Numerical analysis on phase change progress and thermal performance of different roofs integrated with phase change material(PCM)in Moroccan semi-arid and Mediterranean climates

Phase change material(PCM)applied to roofs can weak external heat entering the room to reduce air-conditioning energy consumption.In this study,three forms of macro-encapsulated PCM roofs with different PCMs(RT27,RT31,RT35HC,PT37)are proposed.The effects of PCM thickness,the encapsulation forms,and different PCMs on the thermal performance of the roof are discussed in Moroccan semi-arid and Mediterranean climates.The results show that as the PCM thickness increases,the peak temperature attenuation of the roof inner surface decreases.In two climates,the pure PCM layer among the three encapsulation forms(i.e.pure PCM layer,PCM in aluminum tubes,PCM in triangular aluminum)is the easiest to appear the phenomenon of insufficient heat storage and release,while the reduction of the peak inner surface temperature and time lag is the most satisfying.For the PCM in the aluminum tube,phase change time is the shortest and the latent heat utilization ratio is the highest,while thermal regulation performance is the least satisfying.The PCM in triangular aluminum can improve the latent heat utilization ratio significantly,and its thermal regulation performance is in the middle.In semi-arid climate,the time lag increases with phase change temperature increasing.The time lag could reach up to 6 h with 37℃phase transition temperature.In Mediterranean climate,the longest time lag with RT31 is 5 h,while the lowest peak inner surface temperature appears with RT27.The obtained conclusions could provide guidance for the application of PCM roofs in these two climates.

Overview of Particles and Bubbles in Continuously Cast Steel

This paper gives an overview of phenomena associated with particles and bubbles in continuously cast steel. During steel processing from deoxidation to solidification the inclusion population undergoes changes with opportunities of removal. Flotation is an important separation mechanism. Inclusion particles may accumulate in the solidifying strand, thus forming enriched bands, which depend on the type of casting machine. Bubbles are created during inert gas injection. They also change in size, can float out, but also form accumulation bands. The interaction of bubbles and particles is discussed. Internal structure that recently has been observed on the inner surface of bubbles will be reviewed.

NiCo_(2)O_(4) hollow microsphere-mediated ultrafast peroxymonosulfate activation for dye degradation

Morphology and dispersity are key factors for activating peroxymonosulfate(PMS).In this study,we designed a recyclable open-type NiCo_(2)O_(4) hollow microsphere via a simple hydrothermal method with the assistance of an NH_(3) vesicle.The physical structure and chemical properties were characterized using techniques such as scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),N2 adsorption and X-ray photoelectron spectroscopy(XPS).The test results confirm that the inner and outer surfaces of open-type NiCo_(2)O_(4) hollow-sphere can be efficiently utilized because of the hole on the surface of the catalyst,which can minimize the diffusion resistance of the reactants and products.Under optimized conditions,the total orga nic carbon(TOC) removal efficiency of rhodamine B(RhB) can reach up to 80% in 40 min,which is almost 50% shorter than the reported values.The reactive radicals were identified and the proposed reaction mechanism was well described.Moreover,the disturbances of HCO_(3)^(-),NO_(3)^(-),Cl^(-)and H_(2) PO_(4)^(-)were further investigated.As a result,HCO_(3)-and NO_(3)-suppressed the reaction while Cl-and H_(2) PO4-had a double effect on reaction.