Taguchi design for optimization of structural and mechanical properties of hydroxyapatite-alumina-titanium nanocomposite

The Taguchi methodology was utilized to determine the influence of three factors, namely nanostructured alumina (A) and micro-structured titanium (B) weight percents and sintering temperature (C) on the phase stability, mechanical and structural properties of hydroxyapatite (HA) composites. HA nanosized powder was synthesized via wet precipitation method. According to L9 orthogonal array, different combinations of powder mixtures were cold isostatically pressed and pressure-less sintered in a reducing atmosphere. XRD analysis confirmed the presence of HA phase and metallic Ti after sintering. Analyze of Variance (ANOVA) method was used to specify the percentage contributions of three factors. Addition of 5–10?wt% titanium contributed to increasing the decomposition of HA and the amount of open porosity by 43.07% and 55.40%, respectively and caused a decrease in the strength by 44.67%. Alumina nanoparticles consistently inhibited the grain growth but showed a negligible effect on the decomposition of HA. It also caused enhancements in the strength and toughness by 14.61 and 23.70% contributions. According to ANOVA, sintering temperature illustrated considerable effects on the properties of HA composites. It exhibited more than 56% contribution to the grain growth and decomposition of HA. Structural investigations led to a total optimum condition with a combination of 7?wt % alumina/3?wt % titanium/1150?°C.     

Evaluation of mechanical properties of polypropylene/polycarbonate/SEBS ternary polymer blends using Taguchi experimental analysis

In this work, ternary polymer blends based on polypropylene (PP)/polycarbonate (PC)/poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) triblock copolymer and a reactive maleic anhydride grafted SEBS (SEBS‐g‐MAH) at fixed compositions are prepared using twin‐screw extruder at different levels of die temperature (235‐245‐255°C), screw speed (70‐100‐130 rpm), and blending sequence (M1‐M2‐M3). In M₁ procedure, all of the components are dry blended and extruded simultaneously using Brabender twin‐screw extruder, whereas in M₂ procedure, PC, SEBS, and SEBS‐g‐MAH minor phases are first preblended in twin‐screw extruder and after granulating are added to PP continuous phase in twin‐screw extruder. Consequently, in M₃ procedure, PP and SEBS‐g‐MAH are first preblended and then are extruded with other components. The influence of these parameters as processing conditions on mechanical properties of PP/PC/SEBS ternary blends is investigated using L9 Taguchi experimental design. The responding variables are impact strength and tensile properties (Young's modulus and yield stress), which are influenced by the morphology of ternary blend, and the results are used to perform the analysis of mean effect as well. It is shown that the resulted morphology, tensile properties, and impact strength are influenced by extrusion variables. Additionally, the optimum processing conditions of ternary PP/PC/SEBS blends were achieved via Taguchi analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of a buffer layer on the structure and the performance of cutting-tools for ZrWN films that are deposited using DCMS and HIPIMS

This paper determines the optimal settings for the deposition of ZrWN nitride films using reactive direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HIPIMS), with pure Zr and W metal targets and Ar plasma and N₂ reactive gases. The materials tested as buffer layers are metal tungsten (W) and tungsten nitride (WN) thin films. Using a Taguchi method, this study determines the effect of deposition parameters for the buffer layer (W DC power, substrate bias, N₂/(N₂+Ar) flow rate and substrate temperature) on the structural and mechanical properties, and the dry machining performance of cutting-tools for multilayer ZrWN/W and ZrWN/WN/substrates. In the confirmation runs using grey Taguchi analysis, there is an improvement of 32.31% and 13.38% in surface roughness and flank wear, respectively. The films are characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (FEI-TEM) and a nanoindenter. The TEM pattern for the ZrWN films shown corresponds to the (111), (200) and (220) planes of the face-center-cubic phase. Pretreatment of a tungsten carbide tool uses oxygen plasma etching to enhance the adhesion of the multilayer ZrWN/WN coating. Compared with coatings that are deposited using DCMS, the samples that are deposited using HIPIMS exhibit a higher film density and a smoother surface. In the HIPIMS mode, the XRD diffraction peaks of the films are sharper and more intense, which indicates an improvement in crystallinity.     

Influence of deposition parameters and annealing treatment on the properties of GZO films grown using rf magnetron sputtering

In this study, transparent conductive films of gallium-doped zinc oxide (GZO) are deposited on soda-lime glass substrates, under varied coating conditions (rf power, sputtering pressure, substrate-to-target distance and deposition time), using radio frequency (rf) magnetron sputtering, at room temperature. The effect of the coating parameters on the structural, morphological, electrical and optical properties of GZO films was studied. This study uses a grey-based Taguchi method, to determine the parameters of the coating process for GZO films, by considering multiple performance characteristics. In the confirmation runs, with grey relational analysis, improvements of 14.1% in the deposition rate, 39.81% in electrical resistivity and 1.38% in visible range transmittance were noted. The influence of annealing treatment, in a vacuum, oxygen, and nitrogen gas atmospheres, at temperatures ranging from 130 to 190 °C, for a period of 1 h, was also investigated. GZO films annealed at 190 °C, in a vacuum, showed the lowest electrical resistivity, at 1.07 × 10⁻³ Ω-cm, with about 85% optical transmittance, in the visible region. It is likely that films grown at lower temperatures (190 °C) could be coated onto polymeric substrates, to produce flexible optoelectronic devices.     

Polymorphism and mechanical properties of syndiotactic polystyrene films

The dynamic-mechanical behaviour and the tensile moduli of unstretched and stretched semicrystalline s-PS films, presenting different polymorphic forms (α, γ, δ and clathrate) but similar crystallinity and orientation, have been compared. The main aim is to elucidate the possible influence of different crystalline phases, being largely different in chain conformation and density, on mechanical properties of s-PS semicrystalline samples. For unstretched films presenting a preferential perpendicular orientation of the chain axes, the highest elastic modulus is observed for films with the high density γ phase while for uniaxially oriented films the highest modulus is observed for films with the trans-planar α phase. As for the clathrate films, the guest molecules when only included into the crystalline clathrate phase, have no plasticizing effect.     

Effects of coating pressure on the thermal and mechanical properties of glow discharge polymer films

The glow discharge polymer (GDP) films for laser fusion targets were successfully fabricated by plasma polymerization technology at different coating pressures. The chemical structure of GDP films was characterized by the Fourier transform infrared (FT-IR) spectrum. The thermal stability was evaluated by thermal-gravimetric analysis (TGA). The mechanical properties were measured by nano-indentation technology. The thickness of GDP films was measured by profile meter. The results show that the deposition rate of GDP films increases with increasing coating pressure. The olefinic structure, the ratio of carbon/hydrogen, and the content of CC in GDP films increase as the pressure increases. At the lower coating pressure, the thermal stability, hardness and Young's modulus of GDP films were well. By calculation, the buckle strength of the GDP films can meet the ICF experiments.     

Effects of nitrogen flow rate on the microstructure and mechanical and tribological properties of TiAlN films prepared via reactive magnetron sputtering

In this study, TiAlN ceramic films were fabricated via reactive magnetron sputtering on a Ti6Al4V titanium alloy substrate. The effects of N₂ flow rates on the microstructure and mechanical and tribological properties of the films were systematically studied. With increasing N₂ flow rate, the films underwent a morphological evolution from a fine columnar structure to a coarse structure with holes and microcracks. In addition, the preferred orientation of the films varied from TiAlN (220) to the (111) plane. However, a high N₂ flow rate (≥20sccm) resulted in target poisoning and reduced the deposition rate, which resulted in defects such as cavities and holes on the surface. Moreover, with increasing N₂ flow rate, the hardness and elastic modulus first increased and then reduced owing to grain refinement. The films deposited at a N₂ flow rate of 16 sccm exhibited the smallest wear width and the lowest wear rate. As the N₂ flow rate increased from 12 to 24 sccm, the wear mechanism of the films changed from abrasive and adhesion wear to abrasive wear caused by severe plastic deformation, which was directly related to the microstructural evolution and mechanical properties.     

Application of Taguchi method for optimization of synthetic rutile nano powder preparation from ilmenite concentrate

In the present research work Taguchi method was applied to investigate the effect of reductive leaching parameters and mechanical pretreatment of ilmenite on nano synthetic rutile synthesis. The parameters such as ilmenite to acid mass ratio, ilmenite to iron powder mass ratio, milling time and initial leaching temperature were selected for optimization of experimental conditions. Consequently, the milling time was the most effective parameter on synthetic rutile preparation compared to the rest of the selected parameters. The optimum conditions obtained were as follows: milling in Argon atmosphere 40 min, initial reaction temperature 100 °C, ilmenite to hydrochloric acid mass ratio 1:9.55 and ilmenite to iron powder mass ratio 1:0.075. The characterization of products indicated that the prepared powder with milling time 40 min, temperature 100 °C, ilmenite to hydrochloric acid mass ratio 1:12.8 and ilmenite to iron powder mass ratio 1:0.05 had particles size of less than 100 nm. The analysis further confirmed that synthetic rutile nano powder had 91.1% TiO₂. The nano powder obtained under the optimized condition had a BET surface area of 54.6 m²/g.     

Rapid fabrication of organic/organic photonic bandgap films with tuneable mechanical properties using blended polymer spheres

In this study, the photonic bandgap (PBG) film with tunable mechanical properties and photonic stop band was prepared by a simple and feasible approach. Colloid polymer spheres with a relatively large diameter (approximate D_n of 200 nm) and different glass transition temperatures (T_g) were blended with small polystyrene (PS) latex (D_n = 20 nm) and were subsequently casted on a substrate for 3 h at 50°C for self‐assembly of the PBG film. The monodispersed polymer spheres were synthesized by soap‐free emulsion polymerization in the boiling state. The T_g values of the spheres were predetermined based on the Fox equation, and designed to fall in the region of ?34°C to 112°C. Small PS could also be synthesized by this approach using the comonomer, sodium p‐styrenesulfonate (NaSS), to ensure the small diameter. The long‐range ordered structure constructed by embedding the small PS in the PBG film was indirectly confirmed on the basis of SEM analysis, from which the monochromatic film color was determined based on Bragg's diffraction law. Tunable film color was achieved by adjusting the diameter of the spheres, as evaluated using UV–Vis. Tunable mechanical properties of the PBG film were also achieved by varying the T_g of the spheres or the filling ratio of small PS. Based on these approaches, the ultimate tensile strength could be tuned in the region between 0.39 to 4.7 Mpa, and the relative strain could be varied from 1236% to 16%, illustrative of the excellent deformability of the film. Furthermore, by variation of these two parameters, the film properties could be changed from typical elastomer behavior to brittle plastic polymer type behavior, greatly extending the prospective application fields. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40276.     

Paper-like graphene-Ag composite films with enhanced mechanical and electrical properties

In this paper, we have reported that paper-like graphene-Ag composite films could be prepared by a facile and novel chemical reduction method at a large scale. Using ascorbic acid as a reducing agent, graphene oxide films dipped in Ag⁺ aqueous solutions can be easily reduced along with the decoration of different sizes of Ag particles distributed uniformly. The results reveal that the obtained films exhibit improved mechanical properties with the enhancement of tensile strength and Young''s modulus by as high as 82% and 136%, respectively. The electrical properties of graphene-Ag composite films were studied as well, with the sheet resistance of which reaching lower than approximately 600 Ω/□. The graphene-Ag composite films can be expected to find interesting applications in the area of nanoelectronics, sensors, transparent electrodes, supercapacitors, and nanocomposites.     

聚乙二醇改性壳聚糖薄膜结构与性质的研究

将壳聚糖与聚乙二醇进行共混,利用溶剂挥发成膜法制备了壳聚糖/聚乙二醇二元共混薄膜。通过红外光谱、偏光显微镜、AFM等研究了共混膜的表面形貌、微结构及力学性能。结果表明:聚乙二醇可明显改善壳聚糖薄膜的脆性,当w(PEO)≤20%时,共混物各组分间有较好的相容性。偏光显微镜照片显示共混膜中聚乙二醇颗粒结晶结构随着聚乙二醇量的增加变得更为完整。     

Insights into the thermo-mechanical properties of films cast from emulsion terpolymers

Emulsion polymerization is among the most used processes at the industrial level for the production of a wide range of polymers. The films cast from such emulsions are widely used in coatings industry and their thermo-mechanical properties are extremely important. In this work, n-butyl acrylate was copolymerized with different monomers (styrene, methyl methacrylate and acrylonitrile) in emulsion polymerization, using reaction conditions feasible to be applied at the industrial level. The films cast from the emulsions were characterized in terms of their chemical structure and the structure/thermo-mechanical properties relationships were studied in detail using different thermal analysis techniques. Both the thermal stability and the thermo-mechanical behaviour showed to be highly dependent on the type of monomers used during the emulsion polymerization. The films showed no melting temperature, indicating that the copolymers formed were amorphous. The elastic modulus and glass transition temperature showed to be dependent on the different percentages of the monomers used in the formulation and it was clearly shown that small changes on composition have strong impact on the mechanical and thermal properties of cast films. To the best of our knowledge, this work presents the first study towards the understanding of the properties of the films obtained from cast acrylic emulsions.     

A new multiscale modeling approach for the prediction of mechanical properties of polymer-based nanomaterials

A detailed knowledge about the physics and chemistry of multiphase materials on different length and time scales is essential to tailor their macroscopic physical and mechanical properties. A better understanding of these issues is also highly relevant to optimize their processing and, thus, their elucidation can be decisive for their final industrial application. In this paper, we develop a new multiscale modeling method, which combines the self-consistent field theory approach with the kinetic Monte Carlo method, to simulate the structural–dynamical evolution taking place in thermoplastic elastomers, where hard glassy and soft rubbery phases alternate. Since the early seventies, it is well established that the properties of the core nanophases in these multiphase materials considerably affect their overall mechanical properties. However, recent experimental studies have clearly demonstrated that, besides the efficient handling of the core nanophases, the appropriate treatment of their interfacial region is another major challenge one has to face on the way of target-oriented development of these materials. In this work, we set a particular focus on the complex structural–dynamical processes occurring at the interphases, and study their influence on the local structural and mechanical properties. To reach our objectives, we apply the new methodology on a thermoplastic elastomer composed of ABA triblock copolymers, subjected to a sizeable external perturbation, and determine its time-averaged internal stress and composition profile. We deduce from this investigation that, to obtain the correct local mechanical properties of these multiphase materials, their structure and dynamics need to be taken into account on an equal footing. Finally, our investigation also provides an explanation and confirms the importance of the chain-pullout mechanism in the viscoelastic and stress relaxation behavior of these materials.     

Structural properties of CoPt films patterned using ion irradiation

Patterned CoPt films were fabricated using a combination of e-beam lithography and He⁺ ion irradiation to produce a planar array of ordered CoPt squares separated by disordered CoPt areas: (i) by molecular beam epitaxy was deposited a CoPt ordered film which corresponds to a “natural” multilayer: alternating pure cobalt and pure platinum (0 0 1) planes. (ii) The film was covered by a 300 nm thick Pt layer mask. (iii) Irradiation with appropriate ion beam and fluence disorders the CoPt film where not protected by the mask. X-ray diffraction, as well as atomic and magnetic force microscopy, is used to characterise the structural and magnetic changes in the film. The He⁺ ion irradiation does not significantly modify the surface of the CoPt film: the roughness almost remains identical (2 nm). This is promising for applications in magnetic recording technologies.     

Taguchi design of experiments for optimization of ionic conductivity in nanocrystalline Gadolinium doped Ceria

Taguchi experiments are designed and carried out for glycine nitrate precursor (GNP) combustion method to study four preparation parameters, viz. Fuel to oxidizer molar ratio, oven temperature, calcination temperature and calcination dwell time for their influence on physical properties and ionic conductivity of sintered pellets of Gadolinium doped Ceria (GDC) powders. These four parameters with their three levels form L9 orthogonal array. Ionic conductivity measurements were done using Nyquist and Bode plots obtained using frequency perturbed impedance analysis in the frequency range of 1 Hz to 1 MHz at temperatures 500–700 °C. The optimum conditions was found out on the basis of ionic conductivity by using ‘larger the better’ analysis. Both, the Analysis of Mean (ANOM) and Analysis of Variance (ANOVA) indicate that Fuel to oxidizer ratio is the only influential process parameter. The ionic conductivity of GDC powder prepared using optimized conditions by Taguchi method was found to be 0.023 S cm⁻¹ at 600 °C, which is 1.5 times higher than earlier measurements. Significantly, this is highest reported conductivity for GDC at 600 °C. The significant improvement in results following Taguchi optimization underlines importance of this method for materials synthesis.     

Barrier and mechanical properties of carrot puree films

The edible films based on carrot puree, carboxylmethyl cellulose (CMC), corn starch and gelatin were developed. Glycerol was added as plasticizer. Hydrocolloids and plasticizer content effects on film properties were investigated. CMC and gelatin contents did not significantly affect film %elongation (%E), oxygen permeability (OP) and water vapor permeability (WVP) but significantly enhanced film tensile strength (TS). Corn starch content significantly enhanced film TS and WVP but not significantly affected film %E and OP. Increasing glycerol content decreased film TS and increased film %E (p < 0.05), OP and WVP. Moreover, the L, a and b values of carrot films increased with the increase of the glycerol and decreased with the increase of the corn starch.     

Microstructure and mechanical properties of in-situ grown mullite toughened 3Y-TZP zirconia ceramics fabricated by gelcasting

In-situ grown mullite toughened zirconia ceramics (mullite-zirconia ceramics) with excellent mechanical properties for potential applications in dental materials were fabricated by gelcasting combined with pressureless sintering. The effect of sintering temperature on the microstructure and mechanical properties of mullite-zirconia ceramics was investigated. The results indicated that the columnar mullite produced by reaction was evenly distributed in the zirconia matrix and the content and size of that increased with the increase of sintering temperature. Mullite-zirconia ceramics sintered at 1500 °C had the optimum content and size of the columnar mullite phase, generating the excellent mechanical properties (the bend strength of 890.4 MPa, the fracture toughness of 10.2 MPa.m^1/2, the Vickers hardness of 13.2 GPa and the highest densification). On the other hand, zirconia particles were evenly distributed inside the columnar mullite, which improved the mechanical properties of columnar mullite because of pinning effect. All of this clearly confirmed that zirconia grains strengthened columnar mullite, and thus the columnar mullite was more effective in enhancing the zirconia-based ceramics. Simultaneously, the residual alumina after reaction was distributed evenly in the form of particle, which improved the mechanical properties of the sample because of pinning effect. Overall, the synergistic effect of zirconia phase transformation toughening with mullite and alumina secondary toughening improved the mechanical properties of zirconia ceramics.     

基于Taguchi方法的微小通道性能分析与参数优化

以高效、紧凑、轻质的航空燃油换热器为研究背景,对影响微小通道换热和压力性能的多种工况条件和结构参数进行探究和优化。应用Taguchi方法的正交实验设计和损失函数分析,得到不同因子对性能指标的贡献度和影响规律,并通过可加性检验证明结论具有统计显著性。结果显示,入口流速和通道流型对微小通道传热和压力性能的贡献度最大,通道流型选择圆柱旋涡发生器通道能获得最佳综合性能。此外发现,换热过程中工质的物性变化会影响普朗特数计算,导致多种传热压力性能和综合性能的评价指标有不同影响规律和不同优化参数组合,因此研究时需要根据实际问题选择恰当的评价指标。     

Improving the mechanical and tribological properties of TiB2/a-C nanomultilayers by structural optimization

A novel nanomultilayered architecture was developed through magnetron sputtering to simultaneously achieve excellent mechanical and tribological properties in TiB₂/a-C film. Structural optimization was conducted by adjusting the modulation period from 1 to 10.5 nm. Film hardness and toughness were significantly improved and reached the optimal value at Λ = 6.6 nm. Combination of a sufficient number of heterointerfaces and appropriate individual layer thickness played a key role in hardening and toughening. The internal stress increased linearly with the increase in modulation period, which may be related to the reduction in the number of interfaces. Furthermore, a low friction coefficient of about 0.1 was achieved in the steady state at Λ ≤ 6.6 nm due to the formation of a uniform and compact transfer film on the worn ball surface. The improved mechanical performance and the presence of an effective transfer film resulted in an outstanding anti-wear performance at Λ = 6.6 nm.