Center Line Average Roughness Research Articles

Deposition of c-axis oriented BaM ferrite layers with low surface roughness on textured underlayers

Ba ferrite layers were deposited on ZnO(001), Au(111), Pt(111), and Pt(100) underlayers using facing target sputtering, and the surface smoothnesses, crystal orientations, and magnetic characteristics were compared. The center-line average roughness R, was smallest at 1.7 nm for a Ba ferrite layer deposited on a Pt(111) underlayer. Ba ferrite layers deposited on underlayers other than Pt(100) exhibited preferential c-axis orientation and their magnetization was mainly oriented perpendicular to the film plane. The smoothest surface, coercivity, as well as high perpendicular and low in-plane coercivity was attained for a Ba ferrite layer deposited on a Pt(111) underlayer.

Gold plating

Electroless Ni–P–Al2O3 composite coatings are popular due to their excellent hardness, friction and wear resistance. The present study tries to investigate the influence of coating process parameters on the surface roughness of electroless Ni–P–Al2O3 composite coating with the help of Taguchi analysis. The different surface roughness parameters considered are, center line average roughness (Ra), root mean square roughness (Rq), skewness (Rsk), kurtosis (Rku), and mean line peak spacing (Rsm). Three parameters, namely, concentration of nickel sulphate as a nickel source, concentration of sodium hypophosphite as reducing agent, and concentration of Al2O3 particles as concentration of second phase particles are considered and fitted into an L27 orthogonal array to find out the optimized condition to minimize the surface roughness of the coating. It is observed that concentration of Al2O3 particles have the most significant influence on Ni–P–Al2O3 composite coating and concentration of reducing agent has moderate influence. The compositional, micro-structural, and phase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction analyzer, respectively.

Preparation and characteristics of Co-Zn ferrite rigid disks without protective layers for high density recording

Spinel type of Co-Zn ferrite films were deposited on glass ceramic disk substrates of 1.89 inch diameter by using a facing targets sputtering apparatus without post-annealing process. Films deposited at substrate temperature T/sub s/ of 200 and 400/spl deg/C were composed of crystallites with clear (111) and (311) orientation, respectively. Disks with (111) orientation (Disk(111)) possessed larger perpendicular component of magnetization than that with (311) orientation (Disk(311)). The center-line average roughness R/sub s/ of Disk(111) and Disk(311) were 1.1 and 4.0 nm, respectively. Their read/write characteristics were examined without protective layer by using a merged type of magnetoresistive (MR) head with shield gap length of 0.27 /spl mu/m. The linear recording density D/sub 50/ increased with decrease of the thickness of recording layer for both disks and the highest D/sub 50/ was 1.36 kfrpi for Disk(111) 50 nm thick and 86 kfrpi for Disk(311) 35 nm thick, respectively.

Characterization and Laboratory Simulation of Turbine Airfoil Surface Roughness and Associated Heat Transfer

The physical characteristics of surface roughness observed on first-stage high-pressure turbine vanes that had been in service for a long period were investigated in this study. Profilometry measurements were utilized to provide details of the surface roughness formed by deposits of foreign materials on different parts of the turbine vane. Typical measures of surface roughness such as centerline average roughness values were shown to be inadequate for characterizing roughness effects. Using a roughness shape parameter originally derived from regular roughness arrays, the turbine airfoil roughness was characterized in terms of equivalent sand-grain roughness in order to develop an appropriate simulation of the surface for laboratory experiments. Two rough surface test plates were designed and fabricated. These test plates were evaluated experimentally to quantify the heat transfer rate for flow conditions similar to that which occurs on the turbine airfoil. Although the roughness levels on the two test plates were different by a factor of two, both surfaces caused similar 50 percent increases in heat transfer rates relative to a smooth surface. The effects of high free-stream turbulence, with turbulence levels from 10 to 17 percent, were also investigated. Combined free-stream turbulence and surface roughness effects were found to be additive, resulting in as much as a 100 percent increase in heat transfer rate.

Preparation of Ferrite Rigid Disks with Isotropy and Read/Write Characteristics

Co-Zn ferrite films were deposited using the facing targets sputtering apparatus and their read/write characteristics were investigated as well as crystallographic and magnetic ones. Co-Zn ferrite films deposited at substrate temperature Ts of 100 and 400 °C revealed very smooth surface and the minimum center-line average roughness Ra were 2.5 and 3.0 nm, respectively. They were composed of crystallites with (111) and (311) orientation and possessed an isotropy and in-plane magnetic anisotropy. High linear recording density of about 114 kFRPI was achieved for specimen disks with (111) orientation which were deposited on fused quartz disk substrate using MIG type head with gap length of 0.27 μm.

The erosion of steel surfaces by grit-blasting as a preparation for plasma spraying

Grit-blasting is commonly used for preparing surfaces for spraying plasma coatings. However, pretreatment by grit-blasting is performed in an empirical and qualitative manner which is often inadequate in the context of modern manufacturing. This paper describes how grit-blasting can be monitored on-line using roughness parameters to specify the surface finish required. The mechanics of grit-blasting are presented in the context of surface roughening. Three classes of roughness parameters are identified and parameters typical of these are related to the surface transformations which occur during grit-blasting erosion. The centre-line average roughness parameter ( R a) is shown to be the best for on-line condition monitoring.

Read/write characteristics of Co-Zn ferrite rigid disks in contact mode recording

Co-Zn ferrite films were deposited at substrate temperature T/sub s/ from 90 to 500/spl deg/C by using facing targets sputtering. Specimen films deposited at T/sub s/ of 200/spl deg/C and below were composed of crystallites with excellent (111) orientation and possessed a very flat surface, where the center-line average roughness R/sub a/ was 2.5 nm. The saturation magnetization 4/spl pi/M/sub s/ took a maximum value of 4.8 kG at T/sub s/ of 250/spl deg/C and the in-plane and perpendicular coercivities H/sub c/spl par// and H/sub c/spl perp// were both 1.5 kOe. A high linear recording density of 105 kFRPI was achieved for a specimen disk with Co-Zn ferrite film deposited at 200/spl deg/C by using a MIG type head with gap length of 0.27 /spl mu/m.

磁性材料の化学 Ｘｅを用いたスパッタリングによる大飽和磁化Ｂａフェライト薄膜の作製と磁気特性

Ba ferrite films were deposited epitaxially on ZnO underlayer from targets with composition of BaO.6.5Fe2O3 using the facing targets sputtering apparatus. The gas mixture of Ar and Xe at 0.18 Pa and O2 at 0.02 Pa was used as the sputtering gas and the dependences of crystallographic and magnetic characteristics on the partial Xe pressure Pxe (0.0-0.18 Pa) were investigated. Films deposited at various Px5 and at substrate temperature of 600°C were composed of BaM ferrite and spinel crystallites, and the minimum centerline average roughness Ra of 8.9 nm was obtained at Pxe of 0.10 Pa and then the saturation magnetization 4πMs, of 5.1 kG and perpendicular anisotropy constant Ku1 of 4.23 × 105 J⋅m-3 were larger than those of bulk BaM ferrite of 4.8 kG and 3.30 × 105 J⋅m-3, respectively. C-axis orientation was observed even for the film deposited at low Ts of 475°C and 4πMs, perpendicular and in-plane coercivity, Hc⊥and Hc//, were 4.7 kG, 2.38 and 0.19 kOe, respectively.

Effect of oxygen on hydrogenated amorphous carbon films

Hydrogenated amorphous carbon (a-C:H) films on a silicon substrate have been prepared from toluene vapour by an r.f. plasma chemical vapour deposition method. The effect of oxygen on the composition and the surface morphology in the a-C:H films has been studied by adding a small amount of oxygen during deposition. Raman spectroscopy showed that the ratio of the amount of sp 3-bonded carbon to that of non-sp 3-bonded carbon is increased by the oxygen addition. By IR absorption measurements, it was found that absorption by the stretching of sp 3-bonded carbon and hydrogen atoms is increased with increasing amount of oxygen added. These results suggest that non-sp 3-bonded carbon is removed by oxygen during deposition. By visible light absorption measurements, it was found that the optical energy gap decreased with increasing amount of oxygen added. Volume resistivity measurements show that the resistivity has decreased with increasing amount of oxygen added. These changes in the optical energy gap and the volume resistivity can be explained by the assumption that hydrogen in the films is removed by oxygen. Observations of the surface by atomic force microscopy revealed that the centre-line average roughness of the films was reduced to approximately one-ninth by oxygen additions. These results show that oxygen addition during deposition plays an important role in removing non-sp 3-bonded carbon and creating a smoother surface.

Evaluation of metallic personalized hemiarthroplasty: a canine patellofemoral model.

The purpose of this study was to characterize the response of articular cartilage to weight bearing against a metallic personalized hemiarthroplasty prosthesis. Ten dogs each underwent surgery in which an elastomeric replica of the left femoral patellar groove was made. Using this replica, a 0.5-mm-thick prosthesis was cast in Co-Cr alloy and subsequently the surface was polished to a mirror finish which had a center line average roughness value in the range of human hemiarthroplasty implants. A second surgery was performed to resurface the left trochlea with this prosthesis. Five animals were sacrificed at 3 months and 5 at 6 months. Cartilage damage occurred primarily in the distal region of the patella, and was especially evident at 6 months. Mechanical indentation tests conducted on patellar cartilage in a saline bath at 37 degrees C indicated both increased deformation and residual deformation in the affected areas, indicative of degenerative change. Areas of fibrillation with a depletion of proteoglycans were identified histologically. These areas were only superficial at 3 months but became more extensive at 6 months. Rheological analysis of the synovial fluid of tests joints indicated that a decrease in viscosity occurred from 3 to 6 months, an additional indicator of progressive degeneration. This novel implant model showed that even if a metallic hemiarthroplasty implant had an identical geometry as the joint surface being replaced and had a reasonably smooth surface, cartilage degeneration inevitably resulted.

めっき法によるCo基非晶質合金薄膜の作製と高周波磁気特性

Co based amorphous films were plated from the bath with phosphorus acid as a metalloid source. The amorphous films with a thickness of about 1μm were successfully fabricated by peeling from a smooth electrode which was mirror-finished so that the center line average roughness was less than 0.5μm. Magnetic properties of these very thin films were examined and a discussion was developed for the relationship between the thickness of the films and the high frequency magnetic properties. The initial permeability of the film with 1μm thickness was high and constant value 3000 at a frequency of up to 10 MHz. Furthermore, the value of tan δ was exceedingly small.

A new device for measuring the real area of contact of polymeric material by the perturbation of total internal reflection

An optical device has been developed to measure precisely and directly the real area of contact (RAC) between a glass prism and a machined polymeric surface. It is based on the perturbation of total internal reflection of a light beam in the region of contact between the two solid surfaces. The optical and electronic components of equipment intended for the measurement of the RAC, given in terms of percentage of the apparent surface of contact, were selected to provide improvements in the way of using this method and have permitted to reach a precision of about 1.5%, and a resolution of 0.05%, for finishes rougher than 1.0μm centre line average roughness value (CLA). These components also ensure measurements with a calibration factor independent of the material considered and its colouration. The design concepts are outlined, and typical experimental results for a thermoplastic material are presented, which show a good performance of repeatability. The variation of RAC with normal load was investigated with a large range of surface roughness of polymeric specimens. The results are included, and show that the real area of contact varies as 0.88 power of the normal load, with a proportionality constant dependent on the roughness of the contacting polymer surface.

Wear properties of silicon nitride in rolling contact

The wear properties of silicon nitride were examined in dry rolling contact. The wear coefficient of silicon nitride in pure rolling was of the order of 10 −6 at the initial stage of wear and of the order of 10 −8 at the steady stage of wear under hertzian pressures of 1.06, 1.30, 1.50 and 1.83 GPa. The wear coefficient of silicon nitride in rolling-sliding was of the order of 10 −3 under hertzian pressures of 1.06, 1.50 and 1.83 GPa. The original grinding marks were decreased by the initial wear. Then a very smooth surface appeared in the steady state and its centre-line average roughness R a was 0.02 μm. In contrast, pitting and the adhesive accumulation of thin film debris on the surface started to occur in the steady stage of wear. Three typical types of wear debris were distinguished. One of these, which was a glassy film, was confirmed to have an SiO 2 structure.

高温疲労破面のＸ線フラクトグラフィ

An X-ray fractographic study was made on the fatigue fracture surface of HT80 and S53C steels at elevated temperatures up to 400°C.Emphasis was put on examing the effects of oxide film and fracture surface roughness on the residual stress and half-value breadth of fracture surface at elevated temperatures. It was found that the oxide film induced on the fracture surface at elevated temperatures was thin enough and was not detrimental for the application of X-ray fractography to analyze the fracture surface of steels up to 400°C.However, it was also found that the increased fracture roughness beyond a certain value was detrimental. The value was estimated as about 7.5μm in the center line average roughness. For this case, it is difficult to apply X-ray fractography because both the residual stress and half-value breadth are controlled not only by Kmax or ΔK but also by the roughness of fracture surface.

切削加工した鋼材の表面残留応力に及ぼすカッター速度の影響に関するＸ線的研究

It is well known that the curved and splitted 2θ vs. sin2ψ distributions are often observed in the surface layers of the uni-directionally machined metallic materials in the case of the X-ray stress measurement. In order to solve this problem, a new X-ray method which provides more informations was proposed previously by Dölle and Hauk.The present experiments were carried out to determine the influence of cutting speed on the residual strain state, half value width of X-ray diffraction lines, micro-vickers hardness and surface roughness in the cut layer of carbon steel S50C.The experimental results showed that the changes in residual strain tensor components ε11, ε22 had similar tendency to those in half value width, micro-vickers hardness and centerline average height roughness in the machining direction.It was also clarified that with an increase in cutting speed, i.e. with a decrease in cutting volume, the residual strain tensor components ε11 and ε22 increased. In some cases, however, the strain increased discontinuously, which was explained by the formation of built-up edge.These results show that the present method of measuring strain tensor is one of the powerful methods to investigate the machining mechanism and surface layer state.

An equation for the centre-line average roughness of material slid against abrasive paper

An analysis was made to determine the magnitude of the surface roughness of a material abraded with an abrasive paper. The theory used in the analysis includes a simple theory of plasticity based on wedge penetration into a soft material. Experimental abrasion test results show that the analysis is useful for the derivation of the centre-line average roughness of material slid against abrasive papers.

Flat-surface wringing and contact error variability

Two highly finished flat surfaces brought into intimate contact by a sliding action in the presence of a trace of liquid develop an adhesive bond of considerable strength in directions both parallel and normal to the interface so formed. This phenomenon has practical importance in length metrology where gauge blocks of hardened steel (often called `slip gauges') are used as working length standards. The adhesive `wringing' bond between their flat smooth surfaces is used to build up a combination or `stack' of these blocks so as to form a standard of any required length by the addition of the individual block lengths. This technique enables the combination to be handled as a single unit without coming apart but it is important to know how consistent this addition is and to quantify the dimensional effect of the `contact error' so introduced.This paper describes a series of experimental investigations which may lead to a better understanding of the physical mechanism of the wringing bond. The contact error has been estimated anew using a surface profile fitting technique made possible by the availability of high-magnification rectilinear traces of the surfaces. From geometrical considerations the minimum value that the contact error can take for two similar surfaces lies between two and four times the centre line average roughness index. The contact error variability with different liquid media, with different gauge block materials and with repeated number of wringings has been studied. The wringing forces increase and the contact error diminishes with time elapsed after wringing. High-magnification rectilinear records of the surfaces show that the surface finish deteriorates with repeated wringing by amounts which are different for different materials but which are enough to affect the repeatability of a wrung-up combination of gauge blocks. A method of contact error comparison by interferometry has been developed and this gives results which are in good agreement with the limits set by surface texture observed when fitting the high-magnification surface profiles. A tentative qualitative theory of wringing, based on the experimental work, is advanced.

ステレオ式ピックアップを使ったラップ加工面あらさの周波数分析

In this report, frequency analysis on some lapped surface roughness are made. The profiles of turning specimens recorded on a magnetic tape are obtained using the stereo type pick-up which is rewired so as to measure the vertical displacement of its stylus.The conclusions obtained are as follows;……1) When logarithmic plot of frequency is taken on the axis of abscissa, frequency analysis curves of lapped surface roughness, that are called spectrum curves, show the Gaussian distribution approximately.This fact concurs with some results of other investigations on periodicity of lapped surface roughness2) The frequency corresponding to the peak position of Gaussian curves is considered to be the mean frequency.3) A constant functional relation between the output voltage at the mean frequency and the center line average roughness is derived.

表面あらさと負荷曲線

The relation between the surface roughness and Abbott's bearing curve is examined by introducing a model of the profile curves of some finished surfaces. Profile curves of almost all kinds of finished surfaces, except such special surfaces as milled ones and turned ones by a round nose tool, can be assumed to be made up of a series of triangles, the height of which is nearly equal with each other. In these cases the bearing curve can be drawn as a main straight line with broken lines at either end of it, and the broken lines disappear when the peaks and the valleys of the cross sectional curve are on two straight lines parallel to the center line of the cross sectional curve. The existence of the broken line has a secondary effect on the estimation of the center line average roughness, while it has important effect on the estimation of the maximum height roughness. Hence the center line average roughness can easily be calculated graphically, neglecting the broken lines of the bearing curve.It is found that the above theory can be applied for the surfaces which are finished by abrasive grains, that is, by emery cloth, abrasive belt, grinding wheel and sand blasting.