Advanced Materials Research Vols. 887-888

Abstract: TiN and TiAlN films have been coated on the surface of tool materials by various methods for the life-time extension of tool. In this work, for the improvement of hardness and adhesion of coating to SKD61 substrate, radical nitriding (RN) of substrate was carried out at 450°C for 5 hours in ammonia gas pressure of 2.7×10³ Pa. The results showed that TiN and TiAlN coatings were distributed uniformly on the SKD 61 substrate. And the film thickness was up to 4 μm, which showed so high deposition efficiency (~ 66.7 nm/min) of arc ion plating at this typical process condition. For both coatings, the TiN phases could be detected and the (111) was dominant crystallite grown orientation. The AlN crystallite structure could be detected as expected in TiAlN film. The critical load of TiN film (22.36 N) was slightly smaller than that of TiAlN film (23.88 N). With increasing the load during scratch test, the friction coefficient of TiN film rose quickly, but friction coefficient of TiAlN had a little change, even decreased slightly.

Abstract: As the goal for aircraft weight reduction and low fuel consumption becomes a dire concern in aerospace industries, there is driving desire for the increasing use of advanced exotic materials such as composites, titanium and Inconels in the aerospace industry because of their high strength to weight ratio. Nevertheless the inherent anisotropy, inhomogeneous properties of CFRP and low bonding strength within the laminates make machining of these composite materials results in several undesirable effects such as delamination, micro-cracking, burr, fiber pull out and breakage. This paper discusses an experimental investigation into the influence of machining parameters on surface roughness when milling CFRP using 4 mm-diameter 2-fluted carbide end-mill coated with Titanium Aluminium Nitride (TiAlN). Relationship between the machining variables and the output variables is established and a mathematical model is predicted for the surface roughness produced during the milling process for the machining conditions investigated.

Abstract: The characterization of guide way joint surface micro-topography is very important for the study of real guide way joint surface. Based on fractal theory, fractal characteristics of rough surface are investigated. The 3D surface topography of specimen which is closed to machine tool guide way both in material and processing condition is obtained by atomic force microscope (AFM). The structure function method is employed to gain fractal dimension and the analysis of fractal characteristics. The results show that meet the processing conditions, the guide way joint surface in the region which can scale show good linear relationship and has obvious fractal.

Abstract: Phosphate conversion coatings was investigated on the surface of AZ91D magnesium alloy in a manganese dihydro phosphate baths. The influence of Ca²⁺ on coating microstructure was evaluate by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques, and the corrosion resistance of the coating was tested by polarization curve methods in 3.5%NaCl. Surface observation results show that the conversion coating presents in crystal feature, and the coating containning Ca was uneven with large grains and small grains. The adding of Ca²⁺ compound in the bath was found to be important for the attainment of good combination between the coating and Mg alloy substrate. Polarization curve results indicate that the phosphate conversion coating containing Ca could enhance the corrosion potential and improve corrosion resistance.

Abstract: Titanium and its alloys have excellent properties and are promising biomaterial in medical engineering field. A bioactive surface on a Ti substrate is a prerequisite for great performance and long service life of implants. Based on the mechanism for inducing cell/tissue responses, three kinds of methods, namely morphological, physicochemical and biochemical methods, are reviewed in this paper. Hybrid methods that integrate individual methods or have additional functions are also discussed.

Abstract: In this paper, a three-dimensional dynamic simulation model is established for a laser heating process taking into account heat flow by conduction and a temperature dependent specific heat capacity in the material. An unorthodox laser beam profile is characterized by two simple beam shape parameters in the model; the difference in energy distributions between the centre and outer edge of the beam and between the leading and trailing edges of the beam is varied by an adjustment of these parameters. In this way, laser surface heating with unorthodox beam profiles is simulated and studied using COMSOL Multiphysics finite element modeling software.

Abstract: The temperature and its distribution of non-isothermal deep drawing mould is one of the key technologies for magnesium alloy sheet forming process. It exerts a tremendous influence on the service life of deep drawing mould and affects magnesium alloy sheet deep drawing effect. An intelligent PID temperature controller with adaptive ability and self-organization was proposed to control the temperature of non-isothermal deep drawing mould, which included disk-shaped resistance heating coils heating die and blank holder, room temperature water cooling punch of the mould. The temperature control system greatly improved the quality of deep drawing parts of magnesium alloy sheet due to its simple structure, high anti-interference and high controlling precision.

Abstract: Micro hydroforming has an ability to manufacture complex 3D micro parts at a high production rate and has drawn increasing attentions. Brief understanding of macro hydroforming, for instance, deep drawing, is necessary to understand the principle of micro hydroforming. Then, special phenomena, such as size effects, occurred at micro scale are discussed and the related theories explaining these phenomena are introduced. Based on the similarities and differences between micro and macro hydroforming, experiments and simulation which consider the size effects are reviewed.

Abstract: Based on Abaqus/Explicit operation platform, a finite element model of Yantai Baosteel Φ460mm PQF mill was established to study the mass scaling factors influence of the rolling process. The experimental results show that mass scaling factor has smaller impact on the temperature. Distortion of rolling force and Mises stress gradually occurs with the increase of mass scaling factor. Under the premise of ensuring the calculation accuracy, a best mass scaling factor is found to improve the computational efficiency of the model.

Abstract: The finished and preformed forgings of the rear lower arm are shown respectively, the shape of the rear lower arm is very complex.The tops of three branch arms are thick lumps and its central part consits of quite thin ribs.This forging is much more slender than the ordinary weldment made of steel plate and its weight is also lightened enormously.It seems that the forging is a limit example of pursuing the weight reduction.By taking great pains in forging scheme and die design,the forging is a success eventually.Simulation results indicate that the essential reason to form lap is the return when the material contacts the ends and the non-symmetrical return intensifies the depth of the lap.The lap was formed at the last moment.According to the simulation results, the dies was ameliorated. Thus,the qualified forging has been obtained eventually.