Taguchi Orthogonal Array Experimental Design Research Articles

Reliability analysis of cutting tools using transformed inverse Gaussian process-based wear modelling considering parameter dependence

Reliability analysis is crucial for ensuring the performability of the desired function. The cutting tool performs the machining operation at varied conditions to manufacture diverse products. During operation, the tool degrades stochastically in the form of wear. To avoid the unfavourable consequences occurring from severe tool wear, appropriate formulation of the tool reliability, considering threshold degradation level as the failure criterion, is crucial. However, the degradation of the tool during machining is impacted by the current state of the tool wear and operating conditions. Considering these, the present study proposes a state-dependent transformed inverse Gaussian (TIG) process incorporating the effects of operating conditions to develop the tool wear model. In order to evaluate the proposed method, tool wear experiments are conducted at different operating conditions following the Taguchi orthogonal array experimental design. The experimental data are utilised to estimate the parameters of the developed model using the Bayesian approach. Following the parameter estimation, tool reliability is evaluated under varying operating conditions. The comparison of the estimated median time to failure of the tools with the failure time observed in the validation experiments ensures the effectiveness of the proposed model. The proposed approach has the potential to estimate the reliability of the industrial products subjected to state-dependent degradation under varied operating conditions.

Utilizing Taguchi method and in situ X-ray powder diffraction monitoring to determine the influence of mechanical activation conditions on the physico-chemical properties and Al leachability of K-feldspar

K-feldspar represents an important natural resource of potassium and aluminum. Within the framework of this study, the K-feldspar was mechanically activated in a planetary ball mill under different conditions planned according to 43 Taguchi orthogonal array experimental design. As outputs, specific surface area (SBET), median particle size (d50), amorphization degree of mineral phases , and Al recovery were used. It was found that the initial d50 value of 293 μm could be reduced to 6.7 μm and the SBET value of 4.7 m2/g could be increased up to 32.5 m2/g upon milling. Both microcline KAl3SiO8, and albite NaAl3SiO8 could be almost completely amorphized, whereas quartz SiO2 still maintained some crystallinity even under the most intensive conditions. Increasing SBET and decreasing the d50 values did not lead to a significant improvement in Al leach recovery, whereas a clear relationship between the amorphization of microcline and the recovered aluminum was found. Analysis of Variance (ANOVA) showed that increasing ball-to-powder ratio is the most beneficial for the improvement in Al recovery. In situ powder X-ray diffraction monitoring performed in an oscillation ball mill under synchrotron irradiation has shown very rapid amorphization of microcline phase at the beginning. However, amorphization of microcline was only partial after two hours of the treatment in this mill, apart from almost complete process in the planetary ball mill. In the end, regressions for the calculation of Al recovery by knowing the values of input parameters were calculated. In general, by just using mechanical activation without the subsequent roasting process that is commonly used to boost metal recoveries, it was possible to quantitatively recover aluminum from K-feldspar.

Parametric Optimization of Powder-Mixed EDM of AA2014/Si3N4/Mg/Cenosphere Hybrid Composites Using Fuzzy Logic: Analysis of Mechanical, Machining, Microstructural, and Morphological Characterizations

This research focuses on a comprehensive exploration of the experimental and mechanical aspects of the electrical discharge machining (EDM) process, specifically targeting the machining characteristics of AA2014/Si3N4/Mg/cenosphere hybrid composites. The aim is to optimize the process parameters for enhanced machining performance through a combination of testing, optimization, and modelling methodologies. The study examines the effects of key EDM variables—peak current, pulse on time, and pulse off time—on critical output responses: surface roughness (Ra), electrode wear rate (EWR), and material removal rate (MRR). Leveraging an L9 Taguchi orthogonal array experimental design, the impact of controllable factors on these responses is analysed. An integrated approach utilizing MATLAB’s logic toolbox and Mamdani’s technique is employed to model the EDM process, and a multiple-response performance index is calculated using fuzzy logic theory, enabling multiobjective optimizations. Furthermore, a mechanical behaviour evaluation of AA2014/Si3N4/Mg/cenosphere hybrid composites is performed through mechanical testing, with a comparison between experimental machining results and predicted values. Scanning electron microscopy (SEM) images reveal the presence of filler reinforcements within the base alloy, displaying an improved microstructure and uniform reinforcement dispersion. An X-ray diffraction (XRD) analysis confirms the major elemental constituents—aluminium, silicon, and magnesium—in the hybrid composites. A microstructural analysis of the hybrid metal matrix composites (MMCs) prepared for EDM showcases closely packed reinforcement structures, circular ash-coloured spots indicating silicon and nitrates, and a fine dispersion of cenosphere reinforcement particles. The study’s outcomes demonstrate a promising application potential for these hybrid composites in various fields.

Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism.

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z1, 7.8-15.6 g/L), seawater-oil temperature (Z2, 25-45 °C), sorbent dose (Z3, 1-3 g), and sorbent particle size diameter (Z4, 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L9(34)) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z1, Z3, and Z4, while the biosorptive capacity is related to Z1 and Z3. The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z1 (7.8 g/L), Z3 (3 g), and Z4 (1.18 mm), as well as at Z1 (15.6 g) and Z3 (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g-1. The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

Synthesis of Kit-6 Magnetite Silica Nanocomposite Functionalized by Amine Group for Removal of Carmoisine Dye from Aqueous Solutions.

In this study, amine-functionalized magnetite Kit-6 silica nanocomposite (Fe3O4@SiO2@Kit-6-NH2) was synthesized as an adsorbent for removing Carmoisine food dye from aqueous solutions. The nanocomposite was chemically synthesized and was characterized by X-ray diffraction analysis (XRD), vibrating sample magnetometery (VSM), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Taguchi orthogonal array experimental design method was used to optimize the experimental conditions, including adsorbent amount, pH of the solution, amount of salt, the volume of sample and contact time. Pseudo first-order, pseudo second-order, intra-particle diffusion and Elovich kinetic models were investigated to study the kinetic parameters of the sorption process. The kinetic data corresponded to the pseudo second-order kinetic model with R2 = 0.9999. Also, adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherm models. The results indicated that the data were well fitted to the Freundlich isotherm model (R2 = 0.9984, n=1.0786). The reusability tests showed that the proposed nanocomposite could be used for more than 8 cycles with removal efficiency higher than 90%. The applicability study of the proposed nanocomposite proved its ability for efficient removal of Carmoisine dye from real aqueous samples.

Synthesis of nano‐sized magnetite mesoporous carbon for removal of Reactive Yellow dye from aqueous solutions

In this study, core‐shell structures of magnetite nanoparticles coated with CMK‐8 ordered mesoporous carbon (Fe3O4@SiO2‐CMK‐8 NPs) have been successfully synthesized for the first time by carbonizing sucrose inside the pores of the Kit‐6 mesoporous silica. The nano‐sized mesoporous particles were characterized by X‐ray diffraction, Fourier transform‐infrared spectroscopy, scanning electron microscope, dynamic light scattering, vibrating‐sample magnetometer, Brunauer–Emmett–Teller (BET) and transmission electron microscopy instruments. The obtained nanocomposite was used for removal of Reactive Yellow 160 (RY 160) dye from aqueous samples. The N2 adsorption–desorption method (at 77 K) confirmed the mesoporous structure of synthesized Fe3O4@SiO2‐CMK‐8 NPs. Also, the surface area was calculated by the BET method and Langmuir plot as 276.84 m2/g and 352.32 m2/g, respectively. The surface area, volume and pore diameter of synthesized nanoparticles (NPs) were calculated from the pore size distribution curves using the Barrett–Joyner–Halenda formula (BJH). To obtain the optimum experimental variables, the effect of various experimental parameters on the dye removal efficiency was studied using Taguchi orthogonal array experimental design method. According to the experimental results, about 90.0% of RY 160 was removed from aqueous solutions at the adsorbent amount of 0.06 g, pH 3 and ionic strength = 0.05 m during 10 min. The pseudo‐second order kinetic model provided a very good fit for the RY 160 dye removal (R2 = 0.999). The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the equilibrium isotherms, and the Langmuir isotherm showed the best fit to data with the maximum adsorption capacity of 62.893 mg/g. Furthermore, the Fe3O4@SiO2‐CMK‐8 NPs could be simply recovered by external magnet, and exhibited recyclability and reusability for a subsequent six runs.

Sulfonic Acid Functionalized SBA-3 Silica Mesoporous Magnetite Nanocomposite for Safranin O Dye Removal

At the present study, sulfonic acid functionalized SBA-3 silica mesoporous magnetite nanocomposite (Fe3O4@SiO2@SBA-3- SO3H) was synthesized and its adsorption ability for removing Safranin O dye from aqueous samples was investigated. X-ray diffraction analysis (XRD), vibrating sample magnetometer (VSM), energy dispersive X-ray spectroscopy analysis (EDX), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the adsorbent. The FESEM images confirmed the synthesis of nanocomposites with good morphology and size below 30 nm. The experimental variables affecting the removal efficiency were optimized by Taguchi orthogonal array experimental design method (L16 array). At the optimal conditions (pH = 6, ionic strength = 0.005 mol L− 1, sample volume = 25 mL, adsorbent weight = 0.12 g and contact time = 15 min) the efficiency for Safranin O removal was obtained as higher than 91%. The pseudo-first-order, pseudo-second-order, intra particle and Elovich kinetic models were investigated, and the kinetic data followed the pseudo-second-order kinetic model (R2 = 0.9999). Also, the study of three isotherm models (Langmuir, Freundlich and Temkin) showed that Freundlich isotherm was suitable for describing Safranin O adsorption (R2 = 0.9941, n = 1.428). The reusability experiments showed high removal efficiency of Safranin O after 9 cycles of usage. Finally, the results of Safranin O removal from the aqueous real samples showed the applicability of this nanocomposite for Safranin O removal applications.

Supersulfated binders based on volcanic raw material: Optimization, microstructure and reaction products

The characterization and optimization of supersulfated binders based on a volcanic material was carried out by Taguchi orthogonal array experimental design, investigating the effects of four factors: type of calcium sulfate, % calcium sulfate, %Portland cement and initial curing temperature. The binders increased strength over time. The statistically defined optimum formulation was: 70%volcanic material-10%Anhydrite-20%Portland cement and curing 22 h at 60 °C then at 20 °C; the predicted and confirmed 28-day strength was 20.2–20.6 MPa; optimum conditions are discussed for other ages. The microstructures and chemical composition of hydration products (EDS) and XRD indicated the formation of C-S-H and ettringite as the main hydration products.

Experimental investigation of machinability parameters in turning of CuZn39Pb3 brass alloy

This paper investigates the machinability characteristics of a high-leaded Brass alloy (CuZn39Pb3) by considering the effect of rotational speed; feed rate and depth of cut on main cutting force Fc, arithmetic surface roughness Ra and maximum height of profile Rt during its longitudinally turning. An L18 mixed-level Taguchi Orthogonal Array experimental design was established so as to systematically examine the effect of machining conditions on the aforementioned responses. Full quadratic regression models were developed for correlating the experimental and fitted data after the statistical analysis for studying the significance of the cutting conditions to main cutting force Fc, arithmetic surface roughness Ra and maximum height of profile Rt. Experimental results have shown that depth of cut holds dominant effect of cutting force whilst its contribution equals to 73.61%. Rotational speed and feed rate have just as important effect on arithmetic surface roughness average with 38.85% and 32.15% contributions respectively. For the maximum height of the profile, rotational speed has a significant contribution equal to 42.38% of the overall significance. The models created can explain the investigated parameters’ variation to the percentages of 99.44%, 97.29% and 96.76% for main cutting force Fc, arithmetic surface roughness Ra and maximum height of profile Rt respectively.

Enzymatic extraction and characterization of polysaccharide from Tuber aestivum

Tuber aestivum is one of the important edible mycorrhizal truffle having unique flavor and texture. It is known to contain approximately 5.23% of polysaccharide. The present work was focused on extraction and characterization of the polysaccharide from fruiting body of T. aestivum. The polysaccharide was extracted using complex enzymes viz. papain, trypsin and pectinase. Taguchi orthogonal array experimental design and response surface methodology were employed to optimize the factors involved in the extraction process. The optimal factors for the extraction of polysaccharide from T. aestivum were 1.0% trypsin, 2.0% pectinase, 1.0% papain, temperature 50°C, pH 6.0 and extraction time 90min. Under these optimum conditions the polysaccharide extraction yield was found to be 46.93% of total polysaccharide. Polysaccharide so obtained was characterized for its structure, chemical composition, thermal analysis and bioactivity. The monosaccharides present in the extracted polysaccharides were glucose (>90%), rhamnose, galactose and mannose. The polysaccharide extracted from T. aestivum possessed the significant in vitro antioxidant capability.

Visible light photocatalytic activity of chitosan/poly(vinyl alcohol)/TiO2 nanocomposite for dye removal: taguchi‐based optimization

This work describes the preparation of chitosan/poly (vinyl alcohol)/titanium dioxide (CS/PVA/TiO2) nanocomposite for its use as a photocatalyst under visible light irradiation. The prepared nanocomposite was characterized by Fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of CS/PVA/TiO2 was evaluated by photocatalytic removal of acid red 14 (AR14) in aqueous solution as a model pollutant. A Taguchi orthogonal array experimental design with an L16 matrix was employed to optimize the factors affecting the photocatalytic efficiency of CS/PVA/TiO2 nanocomposite such as: pH, irradiation time, initial dye concentration, and nanocomposite dosage. The optimum conditions were found to be as follows: pH = 3; irradiation time = 120 min; initial dye concentration = 10 mg L−1, and nanocomposite dosage = 400 mg L−1. The pH was found to be the most effective factor for dye removal, followed by the nanocomposite dosage. The dye removal during visible‐CS/PVA/TiO2 process under optimal conditions followed the pseudo‐first‐order reaction model with the rate constants of 0.0188 min−1. The photocatalytic activity of CS/PVA/TiO2 nanocomposite dropped very slightly in five consecutive reaction cycles. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 66–72, 2017

Adsorption of cefixime from aqueous solutions using modified hardened paste of Portland cement by perlite; optimization by Taguchi method.

In the present study, we have used a simple and cost-effective removal technique by a commercially available Fe-Al-SiO2 containing complex material (hardened paste of Portland cement (HPPC)). The adsorbing performance of HPPC and modified HPPC with perlite for removal of cefixime from aqueous solutions was investigated comparatively by using batch adsorption studies. HPPC has been selected because of the main advantages such as high efficiency, simple separation of sludge, low-cost and abundant availability. A Taguchi orthogonal array experimental design with an OA16 (4(5)) matrix was employed to optimize the affecting factors of adsorbate concentration, adsorbent dosage, type of adsorbent, contact time and pH. On the basis of equilibrium adsorption data, Langmuir, Freundlich and Temkin adsorption isotherm models were also confirmed. The results showed that HPPC and modified HPPC were both efficient adsorbents for cefixime removal.

Determination of sulfonylurea herbicides in soil samples via supercritical fluid extraction followed by nanostructured supramolecular solvent microextraction

The present work describes a sensitive procedure for extraction and determination of three sulfonylurea herbicides (metsulfuron-methyl, bensulfuron-methyl and chlorsulfuron) in water samples using supramolecular solvent microextraction. A supramolecular solvent with a nano structure made up of decanoic acid assemblies dispersed in tetrahydrofuran and water was proposed. Also, a supercritical fluid extraction coupled with supramolecular solvent microextraction was applied for extraction and determination of ultra-trace amounts of sulfonylurea herbicides in soil samples. A Taguchi orthogonal array experimental design with an OA16 (45) matrix was employed to optimize the supercritical fluid extraction conditions. In supercritical fluid extraction–supramolecular solvent microextraction procedure, a mixture of decanoic acid and the SFE collecting solvent (tetrahydrofuran) was added to water for supramolecular solvent formation. The effective parameters on the supramolecular solvent microextraction efficiency were studied and optimized using two different optimization methods: one variable at a time and face centered design. Under the optimum conditions, linear dynamic ranges varied within 0.1–5mgkg−1 (0.9978≤R2≤0.9987) and 0.5–100μgL−1 (0.9973≤R2≤0.9995) for all of the sulfonylurea herbicides in the supercritical fluid extraction–supramolecular solvent microextraction and supramolecular solvent microextraction, respectively. The intraday (n=5) and interday standard deviations were calculated by extracting the SUHs from water and soil samples through supramolecular solvent microextraction and supercritical fluid extraction–supramolecular solvent microextraction. Interday RSDs% lower than 7.1% and intraday RSDs% lower than 3.8% were obtained. Limits of detection, based on a S/N ratio of 3, were 0.5μgL−1 and 0.7mgkg−1 for supramolecular solvent microextraction and supercritical fluid extraction–supramolecular solvent microextraction, respectively.

Equilibrium sampling through membrane based on a hollow fiber for determination of naproxen and diclofenac in sludge slurry using Taguchi orthogonal array experimental design

A three-phase hollow fiber liquid phase microextraction (HF-LPME) method was evaluated for the extraction and preconcentration of naproxen and diclofenac using a polypropylene membrane followed by analysis using HPLC or LC/MS. In this technique, the drugs were extracted into di-n-hexyl ether immobilized in the wall pores of a porous hollow fiber from 50 mL of sludge slurry sample as a donor phase with pH 3, and then back-extracted into the acceptor phase located in the lumen of the hollow fiber. Experimental factors were studied in 16 trials using a Taguchi orthogonal array experimental design with an OA16 (45) matrix. The significance of these factors was investigated using analysis of variance. The extraction time was statistically demonstrated as the main factor for the extraction of naproxen and diclofenac, while ionic strength played the role of the second most important factor for HF-LPME extraction of diclofenac. The method permitted a detection limit of 0.2–0.7 ng g−1 with relative standard deviation values of 3–5%. Enrichment factors of 2,300 for naproxen and 1,400 for diclofenac were achieved. The method was applied to determine naproxen and diclofenac in sewage sludge from sewage treatment plant, Källby (Lund, Sweden).

Preparation and evaluation of thermally stable nano‐structured self‐doped polythiophene coating for analysis of phthalate ester trace levels

Nano-structured self-doped polythiophene (SPT) electrodeposited in the presence of fluorinated organic acid was applied as a thermally stable conductive polymer-based solid-phase microextraction (SPME) fiber candidate. Quantitative determination of trace levels of phthalate esters including dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and diethylhexyl phthalate (DEHP) was carried out using this novel fiber, coupling with gas chromatography-flame ionization detector (GC-FID). The SPT coating was proved to be stable at high temperatures (∼350°C) with a high extraction capacity and long lifetime (more than 60 times). Improved temperature resistance was obtained by the presence of sulfonated groups in the backbone of polymer. Thermal stability of novel SPT was superior to common polythiophene (synthesized in LiClO(4) ). The extraction procedure was optimized by means of the Taguchi orthogonal array experimental design with an OA(16) (4(5) ) matrix including extraction temperature, extraction time, salt concentration, stirring rate, and headspace volume. The good linearity was obtained for most compounds with correlation coefficients (R(2) ) of between 0.993 and 0.995. The detection limits were lower than 0.12 ng/mL for dimethyl phthalate, DEP, dibutyl phthalate, and diethylhexyl phthalate. The method was successfully applied to the analysis of water samples with the recoveries from 90±1 to 107±1%.

Terpenes: Effect of lipophilicity in enhancing transdermal delivery of alfuzosin hydrochloride

Transdermal drug delivery has attracted much attention as an alternative to intravenous and oral methods of delivery. But the main barrier is stratum corneum. Terpenes classes of chemical enhancers are used in transdermal formulations for facilitating penetration of drugs. The aim of the study is to evaluate terpenes as skin penetration enhancers and correlate its relationship with permeation and lipophilicity. In this study, alfuzosin hydrochloride (AH) hydrogels were prepared with terpenes using Taguchi orthogonal array experimental design. The formulations contained one of eight terpenes, based on their lipophilicity (log P 2.13-5.36). The percutaneous permeation was studied in rat skin using diffusion cell technique. Flux, cumulative amount, lag time and skin content of AH were measured over 24 hours and compared with control gels. Nerolidol with highest lipophilicity (log P 5.36 ± 0.38) showed highest cumulative amount (Q24) of 647.29 ± 18.76 μg/cm2 and fluxrateof 28.16 ± 0.64 μg/cm2/hour. It showed decreased lag time of 0.76 ± 0.15 hours. Fenchone (2.5%) (log P 2.13 ± 0.30) produced the longest lag time 4.8 ± 0.20 hours. The rank order of enhancement effect was shown as nerolidol > farnesol > limonene > linalool > geraniol > carvone > fenchone > menthol. Lowest skin content was seen with carvone. Increase in lipophilicity of terpenes showed increase in flux, cumulative amount (Q24), and enhancement ratio which was significant with P < 0.000. But lag time was decreased and no correlation was found between lipophilicity and skin content. Histological studies showed changes in dermis which can be attributed to disruption of lipid packing of stratum corneum due to effect of nerolidol within lipid lamellae. It was found that small alcoholic terpenes with high degree of unsaturation enhance permeation of hydrophilic drugs, liquid terpenes enhance better than solid terpenes and terpenes with high lipophilicity are good penetration enhancers.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater-Part II

In Part I of this work, we identified four important process, base sheet, and formulation variables that strongly influence the runnability of a curtain coater at high speed, using a Taguchi orthogonal array experimen-tal design approach. The effects identified are base sheet roughness, coating rheology, curtain height, and the amount of steam applied in the boundary layer air removal system (steam substitution system [SSS]). In the second phase of our study, we examine the contribution of these four variables on curtain coating stability in more depth using a D-optimal design of experiment. The results show the set-up of the boundary layer air removal system to be the most critical variable to maintaining the stability of the curtain. We found base sheet roughness, in combination with the parameters of the coating formulation, to also be very important. Coating coverage improved with the smoothness of the base sheet and excellent coating coverage was attainable at low coat weights. A shear thinning coating was found to provide the most favorable coating rheology for curtain stability at high speeds.

Medium optimization of Rhodococcus erythropolis LSSE8-1 by Taguchi methodology for petroleum biodesulfurization

High production of Rhodoccus erythropolis LSSE8-1 and its application for the treatment of diesel oils was investigated. Culture conditions were optimized by Taguchi orthogonal array experimental design methodology. High cell density cultivation of biocatalyst with pH control and fed-batch feeding strategies was further validated in a fermentor with the optimal factors. Cell concentration of 23.9 g dry cells/L was obtained after 96 h cultivation. The resting cells and direct fermentation suspension were applied for deep desulfurization of hydrodesulfurized diesel oils. It was observed that the sulfur content of the diesel decreased from 248 to 51 μg/g by two consecutive biodesulfurizations. It implied that the biodesulfurization process can be simplified by directly mixing cell cultivation suspension with diesel oil. The biocatalyst developed with the Taguchi method has the potential to be applied to produce ultra-low-sulfur petroleum oils.

The production and characterisation of chemically reactive porous coatings of zirconium via unbalanced magnetron sputtering

High surface area, reactive coatings have many applications. Magnetron sputtering has the potential to produce, on an industrial scale, highly porous coatings. A programme of work has been commissioned concerning high surface area coatings and the work reported here forms part of this project. The technique of unbalanced magnetron sputtering is being used to produce porous oxygen-sensitive coatings of zirconium and titanium. Taguchi orthogonal array experimental design has been used to determine the effects of target-to-substrate separation, orientation of the substrate to the magnetron target, substrate d.c. bias, and pressure, on the coating surface area-to-volume ratio and the initiation temperature of the reaction in air. Different techniques for determining the comparative surface areas have been investigated. These include comparisons from SEM micrographs and electrochemical techniques. Initial results indicate that magnetron-to-substrate orientation and substrate bias have the most significant effects on the coating structure, and the target-to-substrate separation was found to have little effect over the range investigated. Differential scanning calorimetry was performed on coatings deposited onto freshly cleaved sodium chloride substrates, and the trends of reaction temperatures against the four experimental factors were compared with comparative surface areas.