Papers by Keyword: Surface Topography

Abstract: Nowadays, plastics have become one of the most demanded materials, replacing the traditional ones such as metals. Therefore, many companies are concerned with the production of plastics, with their distribution and innovation development. Plastics have found utility in a wide range of applications, we use them every day. Measurement of surface roughness of plastic moldings produced by the injection molding process was carried out by a contact profilometer Mitutoyo Surftest SJ401. A reason for this measurement is to obtain information about surface roughness. For further technical adjustment is required to have higher surface roughness what helps to increase electrical conductivity of plastic moldings. This involves determination of a ratio between Ra/Rz (the ratio between the arithmetic average of the roughness profile Ra and the average maximum height of the profile Rz) in order to satisfy customer demand for achieving better surface characteristics leading to an increase in electrical conductivity.

Abstract: Laser - cut quality is mainly characterized by a degree of accuracy in shape, size and also by surface layer conditions after cutting associated with surface roughness. An experimental determination of surface tension (or tensor components) of clean metal surfaces is very difficult and there is no direct method for its measurement. Attention was paid to numerical derivation of surface tensions according to the surface topographical features in laser cutting technology. The surface tensions and temperature dependencies of several metallic materials have been determined and confirmed by data obtained from the literature. It was found to be in very good agreement between our results and data from different sources in the literature.

Abstract: A series of novel coated urea, which do no harm to soil, were prepared by the method of melt atomizing coating. The coating is composed of paraffin wax, rosin and the CaHPO4 powder which used as additive. The release characteristics of the coated urea were determined by marinating in water and in soil respectively. Surface and cross-section morphology of the coated urea were studied by scanning electronic microscopy (SEM). The influences of coating content on the nitrogen release rate were discussed. The results indicate that the coating content plays a significant role in the nitrogen release. The results of release data regression show that the nitrogen release behavior of the coated urea could be characterized by the first-order release kinetics; the releasing period in water at 25 is 10.07 d for CRC-25, 17.88 d for CRC-30 when 80% nitrogen was released, respectively. And the releasing period in soil at 25 °C is over 130 d for the two coanted urea; the SEM for the coated urea show that the aperture in the membrane is less than 2 μm.

Abstract: Running-in is an important and inevitable wear process for machine system, and it plays an indispensable role in extending service life and improving operating performance. Surface topography appears as a significant feature of friction pairs. Therefore, study on modification of surface topography in running-in is crucial to control surface quality and then achieve improvement of machine system. In this paper, to understand the evolution of surface topography in running-in process, steel dry sliding running-in experiments were conducted, and surface topographies in running-in were evaluated with the areal surface evaluation parameters. The results reveal that surface topography evaluation could provide valuable information about wear status of steel running-in process of dry sliding friction, amplitude parameters, area and volume parameters, and hybrid parameters play different and important roles in characterization of surface topography modification in running-in.

Abstract: To investigate the characteristics of material removal mechanism in the continuous contour control grinding. It is simplified as a variable speed single grit scratching the surface of quench hardening AISI 5140 steel. Utilizing optical microscope, optical profiling system and displacement transducers, the scratch morphology and force were analyzed with applied normal load (depth) and scratch separation distance. Piles-up at the sides of the groove is no obvious change with traverse speed pulse. Both the normal force and the tangential force increase with an increase in traverse speed and depth. The change of traverse speed leads to force fluctuating, and then the forces fall down rapidly to a constant value relatively.

Abstract: The Pd/Sn catalytic coating on graphite electrode had been synthesized by chemical plating in this paper. Scanning electron microscope(SEM)and Electrochemical workstation(EW)were used to analyze the coating surface topography and electro-catalytic properties of modified graphite electrode with and without the coating. Results show that Pd and Sn are in the form of spherical particle and completely cover the surface of graphite electrode includes concave defects. Most Pd and Sn particles are dispersive ones of size of about 70 nm and few of which are polymerized in island forms. The peak value of current density increases with scanning speed, which goes positive potential scanning. Further more, the peak current increases with the concentration of NaOH solution, which shows nonlinear relationship between peak current and solution concentration, The peak current increases more rapidly with solution concentration increases in low NaOH concentration solution than that in high NaOH concentration solution.

Abstract: The drilled surface characteristic of epoxy resin reinforced by multi-directional carbon fibers is investigated based on experiments. With the emphasis on the effect of fiber direction, the mechanism of inhomogeneous surface topography is discussed. Besides, the mechanism of drilling-induced delamination and splitting defects are analyzed, and the drill condition and drilling parameters are also considered. It is indicated that the varied fiber direction is the main cause resulting in the inhomogeneous topography; delamination is easy to occur between two adjacent laminas which have different fiber directions, and it is more serious near the exit of drilled hole.

Abstract: At the neck area of dental implant surface, machined surface (Ms) has been employed to avoid surface contamination. Recently, implants which have roughened surface texture (Rs) at their neck are also available. However, from the viewpoint of soft tissue integration, it remains to be elucidated whether or not surface topography affects the soft tissue attachment around implants. The aim of the present study was to clarify the influence of surface topography on peri-implant soft tissue integration. First, surface roughness of both surfaces was measured. Second, protein adsorption capability on both surfaces was examined. Then, as the rat implant model, titanium implants with each surface were inserted into the maxillae. Horseradish peroxidase (HRP) tracer was applied 4 weeks post implantation to the gingival sulci of implants or natural teeth (NT) to investigate the sealing capability of periodontal/peri-implant soft tissue. Collagen density was also observed by fluorescent staining. As a result, surface roughness (Sa) of Ms and Rs was 0.16 µm and 0.25 µm, respectively. Protein adsorption capability on both surface showed no significant differences. In the NT group of the rat implant model, presence of HRP was restricted only in the coronal portion of epithelium. In both implant groups, in contrast, more invasion of HRP was observed in the soft tissue around implants. Especially in the Ms group, more HRP was observed in the deeper area compared with Rs group. Stronger expression of collagen was observed around Rs compared to Ms at the connective tissue-implant interface. It could be speculated that, with dense collagen, Rs implants showed stronger soft tissue integration compared with Ms implants, but the integration is not as strong as NT’s.

Abstract: To study the synthetic topographical characterization of surface created by abrasive water jet (AWJ) and carry out a detailed research for the process of surface creating, this paper researches the surface signals obtained both by contact profiler and a new developed optical instrument. Through wavelet decomposition and re-construction of surface signal, surface features, such as form error, waviness and roughness are separated rationally. Some fundamental issues, such as the selection of wavelet bases and the determination of wavelet decomposition level are discussed in detail.

Abstract: Optical freeform surfaces have a strict request on surface quality, but the vibration of tool , which is often ignored in previous studies, have a great influence on surface topography in micro-milling. This paper constructs a micro-milling motion model concerned with tool vibration, and the impact of tool vibration on feed-interval scallop in micro-milling is analyzed. The results show that tool vibration always lead to an increment of surface roughness; and vibration amplitude and feed per tooth are the major factors that have an effect on feed-interval scallop form and surface quality.