Papers by Keyword: Surface Morphology

Abstract: This Abrasive Water Jet Machining (AWJM) process is usually used to through cut materials which are difficult to cut by conventional machining processes. This process may also be used for controlled depth milling (CDM) of materials. This work primarily focuses on controlling the abrasive flow rate to reduce the time for machining the component. Here, an experimental setup is made with a modified attachment for abrasive feed system to machine for Ti-6Al-4V alloy. The work also investigates the surface morphology, tolerance on depth of machining and surface waviness for the modified setup. With change in mass flow rate of abrasive, the traverse speed is altered and its effects on the machining time are studied. It is observed that traverse speed is an important parameter in the case of CDM for AWJM. It is also shown that surface waviness can be reduced as traverse speed is increased by using modified abrasive feeding system.

Abstract: The effects of different etching temperatures (near room temperature) on the length and surface morphology of SiNWs were reported in this paper. The studies on temperature dependence of SiNWs growth rate were carried out at 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, and 70 °C for n-type and p-type substrates. The results suggested that the SiNWs length could be controlled easily by the change of the etching temperature. Superlong SiNWs were also fabricated by this technique. The superlong SiNWs had the length more than 400 μm and the aspect ratios were about 2000-20000, which could be applied in nanosensors and interconnection.

Abstract: The thin films of W-doped VO₂ were synthesized onto Mo substrates using reactive DC and RF magnetic co-sputtering deposition techniques. The effects of W dopant on the semiconductor to metal phase transition of bare VO₂ were investigated with measuring X-ray diffraction (XRD) , QJ31Wheatstone Bridge and the internal friction and modulus vs temperature. The transition temperatures of VO₂ thin film from monoclinic semiconductor to tetragonal metal are decreased from 68°C to 40°C with the curves of resistance vs temperature and modulus vs temperature. In addition to, the size of grains W-doped VO₂ is more than that of un-doped VO₂, but more smoother.

Abstract: The anatase coatings was obtained by aqua regia dealloying and plasma electrolytic oxidation (PEO) method on NiTi shape memory alloy (SMA) substrate. The PEO manufacturability of NiTi SMA before and after dealloying was researched. The PEO surface morphologies of the aqua regia treated and untreated specimens were investigated with scanning electron microscopy (SEM). The composition of the PEO coatings was investigated with X-ray diffraction (XRD). The element concentration of the surface of the PEO-treated NiTi SMA was measured by an energy dispersive X-ray spectrometer (EDS). The results indicate that the pre-treatment technology by aqua regia dealloying can greatly improve the PEO manufacturability and the PEO morphologies of the NiTi SMA. The optimum dealloying parameters are at room temperature for 10 min. At this circumstance, the PEO manufacturability of the treated samples is most close to that of the industrial pure titanium. There are many honeycomb-like micro-pores in the surface of the PEO coatings, which act as discharging channels. The cracks are invisible in the SEM images of the PEO coatings. The PEO coatings formed on the NiTi is composed of Ti, Ni, Al, O, Au and P. The composition of the PEO coatings is mainly composed of NiTi phase and anatase phase.

Abstract: Titanium is a class of material difficult to common machine. Laser processing is a feasible method for machining of titanium. This paper presents cutting investigation of industry pure titanium sheet with conventional laser and water-jet guided laser, and analyses their processing features by means of the surface morphology of kerf obtained from Scanning Electron Microscope. The result shows that the machining quality and cleanliness of water-jet guided laser processing is much better than conventional laser processing. The impact and cool effects of the high-speeds water jet are more effective to trim the cut surface and remove molten waster.

Abstract: The semiconducting Cu3N films were successfully deposited on glass substrates by reactive radio-frequency magnetron sputtering in a mixture gas of nitrogen and argon. The influence of nitrogen content in a fixed total sputtering gas flow on the preferential crystalline orientation, the mean crystalline grains size, the electrical resistivity, the microhardness, and the reduced modulus were investigated. X-ray diffraction analysis shows that the films were polycrystalline Cu3N and the preferential orientation is greatly affected by the N2 content. The mean crystalline grain size of these as-deposited Cu3N films decrease and the electrical resistivity increase from 1.51×102Ω•cm to 1.129×103Ω•cm with increasing N2 content. And the microhardness and reduced modulus are 6.0GPa and 108.3GPa, respectively. The sectional SEM and planform AFM observations reveal that the films have smooth surfaces with columnar grains.

Abstract: In recent years, variety of environmentally friendly approaches has been studied for effectively controlling biofouling on marine structures. Research on shells surfaces that inhibit marine biofouling has attracted the attention of people. In this study, we take Dosinia japonica as biomimetic object, PDMS as negative material and E44 epoxy resin as positive material. The method of vacuum mixing and casting in zip lock bag was used to obtained biomimetic surface with the microstructure of shell surface. The microstructure of corresponding position was compared by using high resolution digital camera. The LI-3 contact surface profilometer was used to measure its surface morphology and then the data was processed through MATLAB wavelet analysis. Furthermore, the automatic contact angle measuring instrument was adopted to measure the contact angle for comparison. The results show that there are high similarities in multi-scale between resin biomimetic surface and Dosinia japonica surface. We accurately copied the microscopic structure of the shell surface whose hydrophobic performance was slightly better than the shells.

Abstract: This Abrasive Water Jet Machining (AWJM) process is usually used to cut the materials which are difficult to cut by conventional machining processes. In this work, controlled depth milling (CDM) is done using AWJM. This work primarily focuses on controlling the abrasive flow rate to reduce the time for machining the component. Here, an experimental setup is made with a modified attachment for abrasive feed system to machine stainless steel. The work also investigates the surface morphology, tolerance on depth of machining and surface waviness for the modified setup. With change in mass flow rate of abrasive, the traverse speed may also be altered and its effects on the machining time are controlled. This work also employs Non-destructive Testing (NDT) method i.e. ultrasonic flaw detector to find out internal defects and cracks in the milled material.

Abstract: CdS thin films deposited on glass substrate are prepared by chemical bath deposition using the reaction between CdSO₄ and CS (NH₂)₂. The composition, surface morphology and structural properties of as-deposited and annealed CdS thin films were studied using scanning electron microscopy (SEM), X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. The results indicate that the dense, homogeneous polycrystalline CdS thin films with smooth surface can be obtained by chemical bath deposition. The CdS thin films have cubic structure and the ratio of S and Cd is 1:1 in CdS thin films. Optical properties of CdS films were measured with ultraviolet-visible spectrophotometer. The optical band gap energy (Eg) of film sample was found to be 2.31 eV.

Abstract: The magnetic abrasive prepared by sintering method, the aim is to change the internal structure of abrasive particles by sintering method, make the abrasive particles parceled on the surface of magnetic iron particles, and compared with the abrasive particles phase to get a kind of magnetic abrasive particles with high durability, strong magnetic, which can be magnetized in a magnetic field and improve processing efficiency and surface quality in magnetic abrasive machining. Sintering is used to prepare magnetic abrasive in this paper, to make iron particles, abrasive particles mixed with some binder, after suppression, drying, sintering, cooling, crushing and screening. This paper makes analysis for surface morphology and composition of the magnetic abrasive particles by scanning electron microscopy and discusses the effect that the abrasive particles size ratio, sintering time, sintering temperature on the magnetic abrasive, and the preparation of the magnetic abrasive process has been optimized.