Surface roughness of a hot-dipped galvanized sheet steel as a function of deformation mode

A hot-dipped galvanized zinc-coated sheet steel was deformed with three different laboratory test systems: a Marciniak punch system, a flat-die friction test system, and a cupping system. These systems were able to impose various combinations of deformation modes to the sheet. The deformation modes include: (1) strain without die contact, (2) sliding, (3) pressing, and (4) bending. Strain measurements from the electrolitically gridded specimens were made at the same locations as surface profilometry measurements, allowing a direct correspondence of surface roughness with strain. Quantification of the roughening as a function of strain, sliding and bending was determined. The roughening rate depends upon the strain level as well as the strain path. Increased strain without die contact causes an increase in the surface roughness with strain paths close to plane strain exhibiting the highest roughening rate. The deformation modes of sliding, pressing, and bending cause a decrease in the surface roughness (i.e. smoothing) to occur. A first-order model is proposed to account for the surface roughness as a function of these deformation modes.     

磨削参数对陶瓷加工表面粗糙度影响的实验研究

通过对砂轮粒度、砂轮速度、磨削深度、进给速度等4因素及各因素之间交互3水平正交实验的数据分析，证明砂轮粒度对表面粗糙度影响最大，在各因素中起主导作用。发现砂轮粒度和砂轮速度的交互对表面粗糙度的影响大于砂轮速度单因素的影响，粒度和磨削深度的交互对表面粗糙度的影响大于磨削深度单因素的影响，砂轮粒度和工件速度的交互对表面粗糙度的影响大于工件速度单因素的影响。因此，应按砂轮粒度与切削用量的交互对表面粗糙度的影响规律来确定切削用量各参数的选择，而不能按单因素对表面粗糙度的影响规律来确定切削用量参数。     

Surface finish generated in hard turning of quenched alloy steel parts using conventional and wiper ceramic inserts

Significant progress has already been achieved in green manufacturing including dry and hard, often high-speed, machining technologies. For instance, the demand for higher productivity has resulted in the wider application of ceramic and PCBN tools with special multi-radii (wiper) geometry. This paper reports some important characteristics of the surface roughness produced in the turning of a hardened low-chromium alloy steel using mixed alumina–titanium carbon (TiC) ceramic cutting tools equipped with both conventional and wiper inserts. The characteristic geometrical features of surfaces obtained in both these turning operations have been assessed by means of representative two-dimensional (2D) surface roughness parameters, and some 3D visualizations, which allowed more complete characterization of the surface topography and prediction of its service properties. Results show that keeping equivalent feed rates, i.e. 0.1 mm/rev for conventional and 0.2 mm/rev for wiper tools, the surfaces obtained have similar 3D height roughness parameters, and comparable values of skew and kurtosis. At defined cutting parameters, surfaces produced by wiper tools contain blunt peaks with distinctly smaller slopes resulting in better bearing properties. Only marginal changes of Ra parameter were recorded during 15 min machining trials.     

Finishing effects of spiral polishing method on micro lapping surface

This study presents a spiral polishing method and a device for micro-finishing purposes. This novel finishing process has wider application than traditional processes. This offers both automation and flexibility in final machining operations for deburring, polishing, and removing recast layers, thereby producing compressive residual stresses even in difficult to reach areas. Applying of this method can obtain a fine polished surface by removing tiny fragments via a micro lapping generated by transmission of an abrasive medium through a screw rod. The effect of the removal of the tiny fragments can be achieved due to the function of micro lapping. The method is not dependent on the size of the work-piece's application area in order to carry out the ultra precise process. The application of this research can be extended to various products of precision ball-bearing lead screw. The proposed method produces products with greater precision and more efficiently than traditional processes, in terms of processing precisions and the surface quality of products. These parameters used in achieving maximum material removal rate (MRR) and the lowest surface roughness (SR) are abrasive particle size, abrasive concentration, gap, revolution speed and machining time.     

小口径火炮身管振动铰削的实验研究

论文研究了振动铰削降低表面粗糙度的机理，在此基础上通过硬质合金铰刀振动铰削小口径火炮身管的实验，深入分析了振动铰削对火炮身管内膛表面粗糙度的影响。振动铰削把普通铰削的连续切削过程转变为断续的脉冲式切削过程，将普通铰削时的螺旋状连续切屑变成了非常细小的针状单元切屑．增强了铰削加工的断屑排屑能力，从根本上抑制了积屑瘤的形成，避免了已加工表面的犁沟和鳞刺。实验表明，振动铰削的表面粗糙度Ra比普通铰削至少提高三级，振动铰削的表面粗糙度彤值不到晋通铰削Ry值的1／14，振动铰削使孔的已加工表面均匀一致，显著提高了身管内膛的表面质量。     

Effect of substrate surface roughness on the adherence of NiCrAlY thermal spray coatings

The adherence of plasma sprayed NiCrAlY bond coats can be improved by an appropriate substrate surface finish. The interface fracture energy for crack propagation along the coating/substrate interface has been measured for different surface roughness by means of a specially designed four-point bending test. An increase of the interface fracture energy of about 15% was observed for a three times higher surface roughness. In addition, four-point bending tests with the coating on the side face of bending specimens were performed to analyze the fracture and spalling behavior of the coatings both under large tensile and compressive substrate deformations.     

Fuzzy adaptive networks in machining process modeling: surface roughness prediction for turning operations

Due to the complexity of the machine tool structure and the cutting process, the dynamics of machining processes are still not completely understood. This is especially true due to the demand of high-speed machining to increase productivity. In order to model and control these complex processes, new approaches, which can represent complex phenomenon combined with learning ability, are needed. The combined neural–fuzzy approach appears to be ideally suited for this purpose. In this paper, the recently developed fuzzy adaptive network (FAN) is used to model surface roughness in turning operations. The FAN network has both the learning ability of neural network and linguistic representation of complex, not well-understood, vague phenomenon. Furthermore, it can continuously improve the initially obtained rough model based on the daily operating data. To illustrate this approach, a model representing the influences of machining parameters on surface roughness is established and then the model is verified by the use of the results of pilot experiments. Finally, a comparison with the results based on statistical regression is provided.     

Preparation of flee-standing diamond films for high frequency SAW devices

Free-standing diamond films were prepared by hot filament chemical vapor deposition （HFCVD） method under different conditions. Inter-digital transducers （IDTs） were formed on the nucleation sides of free-standing diamond films by photolithography technique. Then piezoelectric ZnO films were deposited by radio-frequency（RF） reactive magnetron sputtering to obtain the ZnO/diamond film structures. Surface morphologies of the nucleation sides and the IDTs were characterized by means of scanning electron microscopy （SEM）, atomic force microscope （AFM） and optical microscopy. The results indicate that the surfaces of nucleation sides are very smooth and the IDTs are of high quality without discontinuity and short circuit phenomenon. Raman spectra show the sharp diamond feature peak at about 1 334 cmI and the small amount of non-diamond carbon in the nucleation side. X-ray diffraction （XRD） patterns of the structure of ZnO/diamond films show a strong diffraction peak of ZnO （002）, which indicates that as-sputtered ZnO films are highly c-axis oriented.     

A comparative study of reactive direct current magnetron sputtered CrAlN and CrN coatings

Approximately 1.5 μm thick CrN and CrAlN coatings were deposited on silicon and mild steel substrates by reactive direct current (DC) magnetron sputtering. The structural and mechanical properties of the coatings were characterized using X-ray diffraction (XRD) and nanoindentation techniques, respectively. The bonding structure of the coatings was characterized by X-ray photoelectron spectroscopy (XPS). The surface morphology of the coatings was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The XRD data showed that the CrN and CrAlN coatings exhibited B1 NaCl structure. Nanoindentation measurements showed that as-deposited CrN and CrAlN coatings exhibited a hardness of 18 and 33 GPa, respectively. Results of the surface analysis of the as-deposited coatings using SEM and AFM showed a more compact and dense microstructure for CrAlN coatings. The thermal stability of the coatings was studied by heating the coatings in air from 400 to 900 °C. The structural changes as a result of heating were studied using micro-Raman spectroscopy. The Raman data revealed that CrN coatings got oxidized at 600 °C, whereas in the case of CrAlN coatings, no detectable oxides were formed even at 800 °C. After annealing up to 700 °C, the CrN coatings displayed a hardness of only about 7.5 GPa as compared to CrAlN coatings, which exhibited hardness as high as 22.5 GPa. The potentiodynamic polarization measurements in 3.5% NaCl solution indicated that the CrAlN coatings exhibited superior corrosion resistance as compared to CrN coatings.     

Technical note: Plasma-sprayed ceramic thermal barrier coatings for smooth intermetallic alloys

A durable ceramic thermal barrier coating is applied directly to a smooth, highly oxidation resistant intermetallic alloy in two layers. The first layer of ceramic is applied by low pressure plasma spraying and the second layer is applied by conventional atmospheric pressure plasma spraying. This approach would allow the use of plasma sprayed ceramic coatings in applications where a metallic bond coat is not desirable.