The FEM model of TiBN and TiBN/TiN coated cutting tool in milling of H13 steel was developed. Process variables such as temperature and stress in the coating layer as well as in the substrate were analyzed. The efficacy of the present FEM analysis was verified by conducting controlled milling experiments on AISI H13 to collect the relevant tool life and force data. The results show that the stress in a coated tool can significantly be reduced compared to uncoated cutting tool, possibly due to surface coatings improving the tribological properties of cutting tools. Coating with good thermal properties also help to improve the thermal behavior of cutting tool.
Cerium-substituted yttrium iron garnet (CexY3−xFe5O12, Ce: YIG) was prepared via coprecipitation. The structure, morphology, valence state and constituent of Ce ions were investigated respectively. X-ray powder diffraction (XRD) analysis shows that Ce: YIG was of single cubic YIG phase. The result of X-ray photoelectron spectroscopy (XPS) indicates the Ce ions in Ce: YIG were in the state of trivalence. Scanning electron microscope (SEM) demonstrates the conglobation of Ce: YIG particles about 0.2μm scale. The magnetic properties were studied by a vibrating sample magnetometer (VSM) and the result exhibits that substitution of Ce3+ changes the magnetic parameters of YIG. The effects of doping content of Ce ions and synthesis temperature on valence control were discussed in detail.
The effects of trace silver and magnesium additions on the microstructure and mechanical properties of the Al−Cu−Li alloys were investigated. The experimental results indicate, that the effect of combined additions of Ag and Mg is the most obvious, the next is that of individual addition of Mg, and that of individual addition of Ag is the least. The addition of Ag and Mg in Al−Cu−Li alloy accelerates the precipitation of T1 and results in increasing the ageing hardness and strength. Prior cold work significantly improves the tensile strength by enhancing T1 precipitation in all the alloys investigated.
The kinetics of internal oxidation of dilute Cu−Al alloys, containing up to 2.214% molar fraction Al, was investigated over the temperature range of 1023 K to 1273 K, and the depth of internal oxidation was measured by microscopies. A modified rate equation was derived to describe the kinetics of internal oxidation of Cu−Al alloy plate. Based on the derived equation, the permeability of oxygen in solid copper was obtained from the internal oxidation measurements. The experimental results show that the depth of the internal oxidation is a parabolic function of time, there is no evidence for preferential diffusion along grain boundaries and an outer layer of pure copper was formed on the external surface of samples.
Green bodies of 25% CePO4/ZrO2 and ZrO2 ceramics were joined at 1450°C for 120 min without applied pressure by using mixed powders slurries composed of CePO4 and ZrO2. The effects of CePO4/(CePO4+ZrO2) ratio of the adhesive on the bond strength of the joints were investigated. Maximum bond strength of 414MPa was obtained by joining an adhesive with the ratio of 0.5. Under the experimental conditions, the grain size of the particles grown in the joint was smaller than that in joined ceramics. The microstructure of the joint was more homogeneous than that of the matrix and without obvious cracks, pores and other defects.
The interaction between precipitation and recrystallization and its effect on the properties of the Cu−Ni−Si−Cr alloy during aging were discussed. The results show that the deformation results in much more dispersed precipitation of the phases. The precipitations have accelerating or retarding effects on the recrysiallization. On the formation and growth of recrystallization, the precipitated phases are coarsed or dissolved in front of grain boundaries following a re-precipitation in the recrystallization area.
The bonding of solid steel plate to liquid aluminum was studied using rapid solidification. The relationship models of interfacial shear strength and thickness of interfacial layer of bonding plate vs bonding parameters (such as preheat temperature of steel plate, temperature of aluminum liquid and bonding time) were respectively established by artificial neural networks perfectly. The bonding parameters for the largest interfacial shear strength were optimized with genetic algorithm successfully. They are 226°C for preheating temperature of steel plate, 723°C for temperature of aluminum liquid and 15.8s for bonding time, and the largest interfacial shear strength of bonding plate is 71.6MPa. Under these conditions, the corresponding reasonable thickness of interfacial layer (10.8μm) is gotten using the relationship model established by artificial neural networks.
Ti/Al2O3 composite with improved mechanical properties was synthesized by the spark plasma sintering. The effect of Nb on the microstructure of the composite was analyzed by TEM, SEM and so on. The experimental results indicate that the bending strength, fracture toughness, micro-hardness and relative density of the composite are 897.29MPa, 17.38MPa·m1/2, 17.13GPa and 99.24% respectively when adding 1.5vol Nb. The bending strength is improved by reason of forming dislocation ring and transfering fracture mode from integranular to mixture fracture of intergranular and transgranular. The crack propagating is mainly the deflection bridging. It indicates a reduction of crack driving force and an increase in crack growth resistance, which results in toughness enhanced.
The synthesis and characterization of PEG-like macromolecular structures on Nitinol surface from tri (ethylene glycol) dimethyl-ether under ECR-cold-plasma conditions were discussed. It was demonstrated that based on high-resolution ESCA, ATR-FTIR and contact angle investigations the deposited PEG-like layers are composed mainly of −CH2−CH2−O− linkages. These structures have a relatively low contact angle. Compared to the unmodified surfaces, the plasma-treated Nitinol, surfaces are more hydrophilic. Plasma enhanced coatings of PEG-like layers can prevent Ni ion from releasing, thereby improving the biocompatibility of Nitinol.
The characteristics of broken surfaces were researched by a scanning electron microscope (SEM) and a reflection microscope, and the fractal dimensions of broken surfaces were measured by the Slit Island method. The experimental results indicate that the broken surface of aluminum electric porcelain is a fractal body in statistics, and the fractal dimensions of broken surfaces are different with the different amplification multiple value. In all of measured fractal dimensions, both of values measured in 100× under reflection microscope and in 500× under SEM are maximum, whereas the values measured in 63× under reflection microscope and in 2000× under SEM are obviously minimum. The fractal dimensions of broken surfaces are also affected by the degrees of gray comparison and the kinds of measuring methods. The relationships between the fractal dimensions of broken surfaces and porcelain bend strengths are that they are in positive correlation on the low multiples and in negative corelation on the high multiples.
Al2O3−SiO2−TiO2−ZrO2 supported membranes were prepared by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al2O3, TiO2 (anatase), Al2SiO5, and ZrO2 in these membranes. Changing the molar ratio of Al:Si:Ti:Zr, the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nonoscale topography and microstructure of membranes were investigated by XRD, SEM, AFM, EPMA. The effects of additives and heat treatments on the surface nanoscale topography and microstructure of composite ceramic membranes were also analyzed.
The residual stresses on the surface of the differently ground and polished silicon nitride ceramics were measured using X-ray diffraction and identified by SEM. The effect of the residual stress on the bending strength was investigated. The investigations show that the grinding process can introduce subatantial tensile residual stresses up to 290 MPa on the surface of silicon nitride ceramics, which has a significant effect on reducing the bending strength of the ceramics after grinding. Thus, in comparison with the ceramics with a rough surface, the ceramics with a mirror image surface may have a lower strength. Polishing can smooth the residual stresses. When we evaluate the quality of the ceramic components after grinding, we must take residual stress into consideration. The grinding methods and grinding conditions must be carefully selected in order to get the fovorite residual stress as well as the surface smoothness.
The influence of mold pressing parameters on the positive temperature coefficient of high-density polyethylenel carbon black composites was investigated. The composites with a low resistivity at room temperature and a high positive temperature coefficient can be obtainee with the mold pressing parameters as follows: mold pressing pressure 6–14MPa, mold pressing temperature 150–170°C, mold pressing time about 15 min, and room temperature of molded specimen after cooding for 20–60 minutes. The positive temperature coefficient effect of the composite is 7.7 when it is prepared under the mold pressing parameters, and the negative temperature coefficient effect is less than 0.8. Scanning electron microscopy (SEM) reveals some aggregations of carbon black particles with a size of 1 μm inside the composite, which was obtained at the mold pressing temperature of 180°C.
Based on the single-chain structure model of magnetorheological fluids, a formula for the calculation of shear stresses was established. The interaction force of two magnetic particles in an infinite single-chain was deduced using a new theoretical model which is founded on Ampere’ molecular current hypothesis, dipole theory and Ampere’ law. Furthermore, the resultant force on a particle was then deduced by taking into account of the action caused by all the other particles in the single-chain. A predictive formula for shear stresses was made corresponding to the case that MR fluids were sheared by a small angle and the calculating results fit well on the order with the yield stresses of the commercial MR fluids.
This investigation aimed at how to improve the hardness and wear resistance by B, Si and Cr, and how to improve the synthesis property by Re (rare-earth element). Based on the experiment of Fe-based alloys of Fe−Cr−Ni−B−Si−Re, through experiments and a serious of synthesis analysis, including surface quality, spectrum composite, micro-hardness, scanning electron microscopy, as well as the synthesis evaluation, etc, prescriptions were optimized. As a result, a Fe−Cr−Ni−B−Si−Re cladding material with a high property was obtained.
The integrated absorption cross section Σabs, peak emission cross section σemi, Judd-Ofeld intensity parameters Ωt (t=2,4,6), and spontaneous emission probability ArR of Er3+ ions were determined for Erbium doped alkali and alkaline earth phosphate glasses. It is found the compositional dependence of σemi is almost similar to that of Σabs, which is determined by the sum of Ωt(3Ω2 + 10Ω4 + 21Ω6). In addition, the compositional dependence of Ωt was studied in these glass systems. As a result, compared with Ω4 and Ω6, the Ω2 has a stronger compositional dependence on the ionic radius and content of modifiers. The covalency of Er-O bonds in phosphate glass is weaker than that in silicate glass, germanate glass, aluminate glass, and tellurate glass, since Ω6 of phosphate glass is relatively large. AR is affected by the covalency of the Er3+ ion sites and corresponds to the Ω6 value.
To study hollow waveguides for CO2 laser transmission, a liquid-phase deposition technique is applied to form a silver film inside silica capillary based on the method of silver mirror reaction. Using this fabrication method, the optimum combination of different parameters is gained and hollow waveguides have been made successfully with a bore size of 1mm and a guide with length of as long as 2m on self-producing apparatus. To meet quality silver film, a relative high temperature, low flowing speed and long time are adopted on the basis of low reactant concentration. The maximum transmission efficiency of hollow-core fiber without dielectric coating can be up to 85 percent and loss can be low to 0.5dB/m, maximum output power is 53W for stable 20 mintues.
The bubble deformation processes were reported when gas was injected into polymer melt flow field in another paper, the experiments showed that the deformation was severely affected by the volume of the bubble, and in turn, for the different bubbles, several different deformation processes were presented during their movement along the flow channel. In addition, we could find that the magnitude of the bubble volume was dependent upon the pressure difference of the gas injection pressure and the melt pressure. In this paper, more experimental conditions were changed to investigate the parameters relevant to the detachment of bubbles from the injection nozzle. The experimental results show that the pressure difference, the melt flow velocity as well as the melt pressure were all critical for the parameters, such as the bubble detachment time, the maximum bubble diameters and the magnitude of the bubble volume. The morphology changes of bubble were very large when the flow field was abruptly changed, and the situations were more complicated.
Fe-6.5wt% Si composite compact was fabricated by spark plasma sintering (SPS). Mechanical alloying (MA) was used to prepare Fe−Si composite powders. The composite powders were sintered by SPS at elevsated temperature from 500°C to 700°C. The experimental results indicate that the non-equilibrium state of composite Fe−Si is preserved in the compact. The density of the bulk rises with the increasing temperature and there is no diffusion of silicon and iron in the interface.
Ordered nanostructure arrays of Ni−Al2O3 were synthesized by direct current electro-deposition in anodic alumina membranes (AAM). The investigation with an electron microscope, an X-ray diffractmeter and a vibration sample magnetometer indicates that the Ni nanowires, growing in the pores of AAM with about 45nm in diameter, are monocrystalline and have a definite preferred crystallizing orientation. The magnetic behavior of the arrays and their mechanism were discussed.
Films were developed from the modified wheat glutens by microbial transglutaminase (MTGase, [E/S]=10u/g, 15u/g and 20u/g) in order to improve physical and barrier properties of the films. Glycerol was used as a plasticizer. The films prepared from the modified-glutens by MTGase show a lower elongation at break(E) and a water vapor permeability (WVP), and a higher tensile strength (TS) than the native gluten films. When the modified gluten films by different concentrations of MTGase are immersed in water at 25°C, their weight losses decreased significantly, and their water resistance increases obviously as expected, compared with the control gluten films. Moreover, an addition of glycerol as plasticizer greatly modified water vapor barrier and mechanical properties of the films.
The montmorillonite was studied by different methods, such as chemical analysis, DAT, TG, XRD, IR, AFM and MAS NMR. The experimental results show that the hydroxyl in octahedra sheets begins dehydrating when the thermal treatment temperature reaches 659°C, but the layer structure remains the same, and the corresponding Al(VI) is turned into Al(IV) in octahedra sheets. When the temperature reaches 900°C, the layer structure of montmorillontite is destroyed, and the new mineral phase μ-cordierite is found. When the temperature reaches 1200°C, the μ-cordierite phase loses its stability, and decomposes into cristobalite phase and mullite phase. Meanwhile, the recrystallization phenomenon in thermal treatment products is obvious. There is a small quantity of AlVI signal in MAS NMR spectrum, corresponding to Al of mullite. When the temperature reaches 1350°C, the cristobalite and mullite phases reduce slightly, and more Fe-cordierite phase appears, corresponding to Fe-cordierite spectrum in XRD and MAS NMR.
The self-healing action of a permeable crystalline coating on the porous mortar was investigated by two times impermeability test. Moreover, the self-healing mechanism of cement-based materials with the permeable crystalline coating was studied by SEM. The results indicate that the permeable crystalline coating not only seals the pores and cracks in mortar during its curing process, but also heals the permeable pathway caused by first impermeability test or cracks produced by freeze-thaw cycles. Therefore, cement-based materials can be improved by the permeable crystalline coating for the self-healing function. SEM images prove that the self-healing function is realized by generating a great quantity of non-soluble dendritic crystalline within the pores and cracks, which prevents the penetration of water and other liquids.
A promising catalytic material, modified gamma alumina with high surface area (300 m2/g) and higher contents of strong acid sites was developed. It was prepared by a special precipitation method with aluminum nitrate solution containing a certain amounts of orthosilicic acid and ammonia aqueous solution. Compared with commercial gamma alumina, the modified gamma alumina is an effective catalyst for dehydration of tetrahydrofurfuryl alcohol to 3,4-Dihydro-2 H-pyran. Under the optimized reaction conditions, an improved yield of 3, 4-Dihydro-2H-pyran of 93.4% was achieved. The profiles of pyridine TPD show that the modified gamma alumina exhibits more strong acid sites than that in the commercial gamma alumina, indicating the strong acid sites on the surface of the catalyst may play a crucial role in this reaction.
Bitumen was modified with desulfurized crumb rubber (DCR) in the present of reactive additives. The effect of the kinds and content of the reactive additive on properties of DCR modified bitumen (DCRMB) was investigated. The morphology of DCRMB was characterized by SEM and the changes of the chemical structure of DCRMB without and with the addition of the reactive additive were analyzed by FTIR. The experimented results show that the softening point, the elasticity recovery and the storage stability of DCRMB were improved significantly by the addition of the reactive additive. This is because that a network structure of rubber in DCRMB was formed and the chemical reaction between C=C double bonds in bitumen and DCR has happened after the reactive additive was added into DCRMB.
The mold filling of RTM was simulated based on the control volume finite element method (CV/FEM). The formulation using isoparametric transformation was discussed in detail and a computational code based on isoparametric technique was developed. The simulation results were compared with experimental data. Different isoparametric elements, quadrilateral and triangular, were compared in the simulation. It demonstrates that the use of bilinear quadrilateral isoparametric elements in simulating the process can produce a higher precision and cost a less time than the use of triangular ones.
Parameters that need to be fitted in High-Strength concrete mix proportion experiment and two equation models that are referenced in the experiment are discussed. The reasoning and implement of the corresponding linear futting algorithm are demonstrated. Parmeter fitting is realized by value estimate method of mathematical statistics. This paper combines mathematical statisitics, linear equations and template thought together successfully and discussed an efficient parameter fitting method based on strength equation model and water consumption equation model.
The method of examining micro-pores in sulphoaluminate MDF cement by means of the Positron Annihilation Technique (PAT) was discussed. The results show that the intensity I2 of positrons annihilation with moderate life-span (τ2≈330Ps) increases regularly with the addition of the numbers of micro-pores (less than 250Å). Therefore, the value of I2 may be used to opitomize the compactness and integrity of the MDF cement structure. At the same time, the experiment result of PAT was compared with that of Mercury Intrusion Porosimeter (MIP).
The mechanism of chloride ion penetration in high performance concrete was analyzed. The experimental results indicate that there are two important reasons that influence the anti-chloride penetration of high performance concrete. One is the function effect of mineral functional material, so that it increases concrete’s capability to resist chloride ion penetration. The other is combined action of mineral functional material’s original capability of binding the chloride ion (physical adsorption) and physicochemical adsorption after hydration.
The addition of graphite powder in conventional asphalt mixture can produced asphalt concrete with excellent electrical performance. Percolation theory was employed to discuss the relation between the conductivity and graphite content of graphite-modified asphalt concrete. It was found that the results of percolation model are consistent with experimental values. The percolation threshold of graphite-modified asphalt concrete is 10.94% graphite content account for the total volume of the binder phase consisting of asphalt and graphite. The critical exponent is 3.16, beyond the range of 1.6–2.1 for the standard lattice continuous percolation problem. Its reason is that the tunnel conduction mechanism originates near the critical percent content, which causes this system to be not universal. Tunnel mechanism is demonstrated by the nonlinear voltage-current characteristic near percolation threshold. The percolation model is able to well predict the formation and development of conductive network in graphite-modified asphalt concrete.
Three cement samples were prepared, including OPC consisted of 100wt% portland cement, PFA consisted of 70wt% portland cement and 30wt% fly-ash, and CA consisted of 70wt% portland cement and 30wt% modified fly ash. The strength of hardened cement paste of these samples was tested and their pore structures were determined by a mercury intrusion porosimeter. Moreover, the data of the pore structures of three samples were comprehensively analyzed. The relations between the pore structures and the compressive strength of the three samples were studied. The experimental results show that the relations between the porosity determined by the mercury intrusion porosimeter and the compressive strength are not notable, and the total pore surface area, the average pore diameter and the median pore diameter could be used to explain the difference of the strength of the tested samples.
The performance of concrete with a new admixture MX was studied by using the freeze-thaw cycle, permeability and chemical attack test. The experimental results show that MX improves the durability of concrete. Within the optimum proportion ranges from 0.1% to 1%, the compressive strength of concrete after freeze-thaw is increased by 20%–50%, and Young’s modulus can be increased by 3.76–5.64 times. The strength and weight loss of concrete with 0.4% MX are respectively decreased by 28% and 60% after hydrochloric acid attack. The strength and weight loss of concrete with 0.4% MX are decreased by 5%–20% after sulfuric acid and sodium sulfate attack. The permeability of concrete with 1% MX at 28 days can be decreased by more than 30%. The investigation of the negative temperature property of MX and analysis on concrete composition and microstructure by MIP reveal that the heat conduction is resisted and the freezing procedure of solution in concrete pore is retarded due to the adding of MX. Moreover, the pore structure of concrete with MX is improved, thus improving the durability. Based on this study, a resistance model of MX to block the heat and mass transference was proposed, and the mechanism of durability improvement of concrete with MX was explained.
The impermeability mechanism of water-proof self-compacting concrete (WPSCC) was studied. The mechanism and influential factors, such as water-cement ratio (w/c), dosage of powder, superplasticizer, sand content, aggregate content, fly ash, UEA, PP fiber, on compactibility and crack resistance of WPSCC were analyzed. A type of WPSCC successfully applied in tunnel liner with its validities, conveniences and economies by mockup test was developed and optimized. Experimental results show that the WPSCC has good workability, mechanical properties and impermeability when reasonable requirements are fulfilled.
The grinding characteristics of two or multi-component material of clinker with limestone, blast furnace slag and fly ash were studied. Investigation was carried out on the particle size distribution, the Blaine fineness and the sieve residue of the separate and interground products. The relative contents of clinker and lime-stone in different size fractions of the interground product were examined, and the interaction of two components, which have different grindabilities, was analyzed. The results show there exists a selective grinding effect during intergrinding, one component can help or hinder the grinding of the other. Making good use of this interaction appropriately not only enhances the grindabilities of two or multi-component mixtures, which can promote the grinding process of clinker with industrial wastes, but also improves their particle size distribution and properties.