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Introduction: By using Cu(NO3)2 as precursor and polyvinylpyrrolidone (PVP) as surfactant, nanosheets of Cu2(OH)3NO3, nanowires of Cu(OH)2 or the mixture of the two were prepared under different molar ratios of OH− to Cu2+. Materials and Methods: The crystal structures and morphologies of the products were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). Results: When the molar ratio of OH− to Cu2+ in reaction solution is lower than 1.28, pure Cu2(OH)3NO3 nanosheets were obtained. The thickness of one piece of nanosheet is about 167 nm. The Cu2(OH)3NO3 nanosheets consists of two types of crystal structures, monoclinic phase and orthorhombic phase. With increase of the molar ratio of OH− to Cu2+, the monoclinic phase of Cu2(OH)3NO3 was transferred to the orthorhombic phase of Cu2(OH)3NO3. When the molar ratio of OH− to Cu2+ is within 1.28-2.24, the product is the mixture of Cu2(OH)3NO3 nanosheets and Cu(OH)2 nanowires. And when this molar ratio is higher than 2.24, only Cu(OH)2 nanowires were produced. The lengths and the diameters of the Cu(OH)2 nanowires are in the region of 50-250 nm and 10 nm, respectively. Conclusion: The reason of the Cu2(OH)3NO3 nanosheets changing into the Cu(OH)2 nanowires is that the OH− anions replace the NO3 − anions in the layered Cu2(OH)3NO3 nanosheets, which causes the rupture of hydrogen bonds connecting the adjacent layers. The Cu(OH)2 nanowires were not stable and found to become spindled CuO nanosheets in air at room temperature.

Lipid crystallization in O/W emulsions is essential to control the release of nutrients and to food structuring. While few information is involved in adjusting and controlling the performance of emulsions by adjusting oil phase crystallization behavior. We herein developed a novel strategy for designing lipid crystallization inside oil droplets by natural waxes to modify the O/W emulsion properties. Natural waxes, the bio-based and sustainable materials, displayed a high efficiency in modifying the crystallization behavior, droplet surface and shape, as well as the overall performance of emulsions. Specifically, waxes induced the formation of a new hydrocarbon chain distances of 3.70 and 4.15 A and slightly decreased the lamellar distance (d001) of the single crystallites, thus forming the large and rigid crystals in droplets. Interestingly, these large and rigid crystals in droplets tended to penetrate the interface film, forming the crystal bumps on the droplet surface and facilitating non-spherical shape transformation. The presence of rice bran wax (RW) and carnauba wax (CW) induced the droplet shape into ellipsoid and polyhedron shape, respectively. Furthermore, the uneven interface and non-spherical shape transformation promoted the crystalline droplet-droplet interaction, fabricating a three-dimensional network structure in O/W emulsions. Finally, both linear and nonlinear rheology strongly supported that waxes enhanced the crystalline droplet-droplet interaction and strengthened the network in O/W emulsions. Our findings give a clear insight into the effects of adding natural waxes into oil phase on the crystalline and physical behavior of emulsions, which provides a direction for the design and control of emulsion performance.

In present work, by employing doping engineering, we demonstrate a new type of organic light-emitting diodes (OLEDs) constructed by novel hybrid electron-injecting and electron-transporting layers (EITL) with cadmium sulfide (CdS) and Alq3 as buffer active materials. Our developed OLEDs exhibit highly effective electron injection from cathode to organic layers. Simultaneously, the driving voltage is significantly reduced with Alq3/Alq3 doped CdS hybrid EITL structure. Importantly, equipped with 60 nm constant thickness of hybrid layer, the device with 15 nm-thickness of Alq3 doped CdS exhibit improved performance than the others with the maximum luminance and the maximum of current efficiency 32340 cd/m2 at 12 V and 5.92 cd/A at 11.5 V, respectively, with the CIE coordinates almost nearby (0.33, 0.56). And at the current density of 200 cd/m2, the current efficiency of the device with EITL was 5.18 cd/A, improved 31% than that of the device non-doped CdS. Such enhanced improvements are attributed to the injection of photo-generated electrons produced by CdS which absorbed the light waves. Our systematic studies and complementary engineering investigations upon highly efficient hybrid OLEDs open new opportunities for innovative applications with optimized integration among performance, dimension and cost in a variety of solid-state lighting field applications, e.g., digital displays, portable systems, smart wearable devices and human–machine interfaces.

Purpose This paper aims to investigate the inhibition effect of sodium silicate (SS), sodium alginate (SA) and sodium tungstate (ST) on the corrosion behavior of AZ91D magnesium alloy in 3.5 per cent NaCl solution through polarization curve test at room temperature, electrochemical impedance spectroscopy and weight loss measurement. Design/methodology/approach The influence of SA concentration on the inhibition efficiency of the corrosion inhibitor was mainly analyzed. The corrosion morphology and inhibition mechanism of the samples were also analyzed with scanning electron microscopy and energy-dispersive spectroscopy. Findings The results show that with the increase of SA concentration, the corrosion inhibition first increases and then decreases. When SA concentration is 0.03 mol/L, the inhibition efficiency is the highest, reaching 98 per cent. The adsorption film formed by SA and other deposition films produce a synergistic effect on the improvement of corrosion resistance of AZ91D magnesium alloy. Originality/value The adsorption film formed by SA with other deposition films produces a synergistic effect on the improvement of corrosion resistance of AZ91D magnesium alloy. With the increase of SA concentration, the corrosion inhibition first increases and then decreases. When the concentrations of SA, SS and ST are 0.03 mol/L, 0.015 mol/L and 0.02 mol/L, respectively, the inhibition efficiency of the inhibitor is the highest, reaching 98 per cent.

The device inserted 0.5 nm thick cadmium sulfide (CdS) as buffer layer, prepared by vacuum thermal evaporation method, has been studied on the non-doped blue organic light-emitting diode. Compared to the device without ultra-thin CdS film, the maximum luminance of the device with ultra-thin CdS film was 11,370 cd/m2 at 11 V, and the maximum current efficiency reached 3.10 cd/A, increased 1.5 times and 1.2 times, respectively. In the optimized devices with the structure of ITO/MoO3 (10 nm)/TPABBI (35 nm)/Bphen (40 nm)/CdS (0, 0.1, 0.3 and 0.5 nm)/LiF (0.5 nm)/Al (100 nm), the effects of CdS layer on the photoelectric performance of the devices were investigated in detail. When the CdS thickness was 0.3 nm, the maximum luminance was 13,590 cd/m2 at 9 V and the turn on voltage was only 3 V. The maximum current efficiency of 3.42 cd/A was obtained. It is indicated that the simple structure of the device with inserted ultra-thin CdS film, cheap and stable inorganic photoelectric material, may be a promising way to fabricate hybrid organic–inorganic LEDs with high performances.

Till now, optical and dielectric constants of polymer based on poly(benzo[1,2-b:4,5-b’]- dithiophene–thieno [3,4-c]pyrrole-4,6-dione) (PBDTTPD) incorporated into thiophene (PBDTTTPD) have not been systematically investigated. In this work, PBDTTTPD thin film was prepared on ITO glass substrate. Transmittance spectra of ITO and PBDTTTPD films were measured. Based on unconstrained optimization method, the glass was firstly as the substrate, the thickness and the refractive index of the ITO were retrieved. Then the refractive index data of the ITO thin film were added to the PUMA program and the ITO was taken as the new substrate, the thickness, optical and dielectric constants of the PBDTTTPD film were further simulated only via the transmittance spectra. These optical and dielectric parameters are promising useful in design optical devices related to PBDTTTPD polymer.

The wet deformation characteristics of coarse aggregates are critical to engineering but have not been well resolved. Therefore, through the large-scale triaxial tests, the sensitivity of the main factors such as initial dry density, initial moisture content, confining pressure and stress level of the filler to the deformation of the wet deformation was analyzed in detail using the orthogonal test method. The results showed that: Among the factors, the primary and secondary factors affecting the axial strain test indexes of each factor are confining pressure> stress level> initial dry density> initial moisture content, and the obtained preliminary law of coarse-grain wet deformation can be coarse-grained roadbed. The design and filling scheme provide important basis.

A uniform CdS nanowires array is grown on the Cd foil through a simply solvothermal method using the Cd foil as the precursor of Cd 2+ and the substrate. The CdS nanowires are perpendicular to the Cd foil and show the preferred (0 0 2) orientation, which have the diameters of ~20–40 nm and lengths of ~10–13 μm. The optical band gap of ~2.46 eV (~505 nm) for CdS nanowires array is obtained by the Kubelka-Munk method. The green and red emissions under the excitation of 420 nm are ascribed to the band gap emission and the transition from the sulfur vacancies to the valence band of CdS nanowire, respectively. The well-aligned CdS nanowires array could be considered to be an excellent candidate for optoelectronic application.

A nano/amorphous-composite film was fabricated by laser cladding (LC) of the Co–Ti–B 4 C–Sb mixed powders on a TA15 alloy. Such film mainly consisted of Ti–Al, Co–Ti, Co–Sb intermetallics, TiC, TiB 2 , TiB, and the amorphous phases. Experimental results indicated that the crystal systems of TiB 2 (hexagonal)/TiC (cubic) and Sb (rhombohedral) played important role on the formation of such film. Due to the mismatch of these crystals systems and mutual immiscibility of the metallic components, Sb was not incorporated in TiB 2 /TiC, but formed separate nuclei during the film growth. Thus, the growth of TiB 2 /TiC was stopped by the Sb nucleus in such LC molten pool, so as to form the nanoscale particles.

Mesoporous molecular sieve MCM-41 was modified by using 3-mercaptopropyltriethoxysilane as a coupling agent and MCM-41 functionalized with sulfonic acid groups was prepared. The prepared product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption technique and temperature programmed desorption. The results showed that during the process of modification the frameworks of the molecular sieve were not destroyed, the channel has ordered property. SH group was successfully grafted to the surface of channels of the molecular sieve. The acid amount on the mesoporous material functionalized with sulfonic acid groups reached 0.755mmol/g, showing a potential application foreground as a catalyst.

The electromagnetic nanocomposites with a core-shell structure are synthesized by in situ chemical oxidative polymerization. The Co doped Fe3O4magnetic particles (Co-Fe3O4) act as the core and poly (3,4-ethylenedioxythiophene)-poly (sodium-p-styrenesulfonate) (PEDOT-PSS) as the conductive polymer shells. The morphology, structure, crystallinity, conductive and magnetic properties were studied by transmission electron microscopy (TEM), Scanning electron Microscope (SEM), Fourier Transform Infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), four-probe conductivity meter and vibrating sample magnetometer (VSM). It is found that the core-shell nanocomposites exhibit controllable electromagnetic properties by adjusting the molar ratio of Co-Fe3O4to EDOT monomer.

Currently, the soil-aggregate mixture has been widely used in some large-scale site preparation projects, compaction characteristics has been pay more attention by many engineers and researchers. However, systematic research is insufficient on how to choose the filler. Moreover, some industry regulations are different on the requirements about filler. This paper relies on a certain big site preparation projects, discussing statistical characteristics and correlation on the maximal grain size, contents of the coarse grain, gradation and other parameters of soil-aggregate mixture. The results show that the maximal and the median grain size have small discreteness and normal distribution, indicating site filler is easy to reach the requirement; The coefficient of curvature, coefficient of nonuniformity and the coarse grain content have large discreteness, and dont obey normal distribution, indicating the filler has large variability. The median grain size is highly relevant to the coarse grain content; the maximal grain size isnt relevant to the coefficient of nonuniformity, the coefficient of curvature and the coarse grain content. According to the results of correlation analysis, we suggest that the importance order follow by coarse grain content, the maximum grain size and gradation for the control parameters of filler. This research may be significant to other similar projects.

The flow field in condensing zone of compact spinning with inspiratory groove was developed with Fluent 6.3 and the distribution of velocity was analyzed too. Also the effect of negative pressure on the yarn quality was analyzed and the experiment was done to prove the effect of negative pressure on the yarn qualities. The results show that the fiber can not be compacted well when negative pressure is too small, but it will add the energy consumption, attach the fibers firmly to the bottom of the compact groove by the effect of flow field and reduce the fiber migration, cause the fibers to be absorbed from the holes or the holes to be plugged when the negative pressure is too big. Therefore, in order to ensure the fibers being compacted well and reduce the energy consumption, the selection of negative pressure in compact spinning with inspiratory groove should be less than -3000pa.

To analyze the structure and performance of Outlast acrylic fiber, the fiber structure was observed respectively by FTIR spectra, X-ray diffraction and scanning electron microscope, the normal physical and mechanical properties were measured, and the thermo-regulated performance was investigated by differential scanning calorimeter, thermal gravimeter analysis and step cooling test. The results indicate that the structure and normal physical and mechanical properties of Outlast acrylic fiber are slightly different from that of normal acrylic fiber. Both the melting peak and crystallization peak of Outlast acrylic fiber are single peaks, and the phase change temperature range is applicable and the phase change enthalpy is high. The decomposition temperature of Outlast acrylic fiber is around 311.85°C. The cooling velocity of Outlast acrylic fiber decreases exponentially with the increase in time, and the thermo-regulated ability of Outlast acrylic fiber is better than that of normal acrylic fiber.

Electron beam surfi-sculpt is a new metal surface processing technology, which is potentially used in many areas. In this paper, forming mechaniam of electron beam surfi-sculpt has been investigated by experiments and numerical simulation. Electron beam surfi-sculpt of Ti-6Al-4V was realized by a new control system and a innovative hexagon scanning waveform. At the same time, microstructure of protrusions was analysed. All the results of experiments and simulation show that forming mechanism is the interaction of vapour pressure and surface tension, but surface tension plays a dominant role during electron beam surfi-sculpt process.

To analyze the structure and thermo-regulated performance of Outlast viscose fiber, the fiber structure was observed respectively by FTIR spectra, X-ray diffraction and scanning electron microscope, and the thermo-regulated performance was investigated by differential scanning calorimeter, thermal gravimeter analysis and step cooling test. The results indicate that the structure of Outlast viscose fiber is similar to that of normal viscose fiber. Both the melting peak and crystallization peak of Outlast viscose fiber are double peaks, and the phase change temperature range is applicable and the phase change enthalpy is high. The decomposition temperature of Outlast viscose fiber is about 280-320°C. The cooling velocity of Outlast viscose fiber decreases exponentially with the increase in time, and the thermo-regulated ability of Outlast viscose fiber is better than that of normal viscose fiber.

Temperature dependence of dark conductivity and photoconductivity has been studied in amorphous InSb thin films in the temperature range of 120–300 K. The experimental data suggest that conduction in the high temperature range occurs in the extended states; conduction in the intermediate temperature range is due to thermally assisted tunneling of charge carriers in localized states near the band edge; while conduction in low temperature range takes place through variable range hopping of charge carriers in the localized states near the Fermi level. The temperature dependence of photoconductivity shows that the temperature region is divided into two regions. Moreover the result of intensity dependence of steady state photoconductivity indicates that bimolecular recombination at high temperatures and monomolecular at low temperatures in amorphous InSb thin films.

Amorphous InAsSb films and hydrogenated InAsSb films are deposited on substrates of quartz glass and silicon by rf magnetron sputtering technique in different gas ambient. The effect of H addition on structure, optical properties and electrical properties of a-InAsSb is studied. It is found that the bonded hydrogen content increases with increasing H2 to Ar flow rate radio(R). When R is 0.1, Hydrogen addition shifts the optical absorption edge to higher energy, decreases the dark conductivity and improves the photo-sensitivity. However, hydrogen addition produces the crystallization of the film at R>0.1. Moreover the optical gap, dark conductivity and photo-sensitivity of the films have a reverse change compared with that in R=0. These results demonstrate that hydrogen has obvious passivation effects on rf sputtered amorphous InAsSb thin films only at R=0.1.

We present a systematic study of the effect of the sputtering parameters on the structure and composition of InSb film. The effect of the sputtering parameters on the crystallographic structure of InSb films is discussed in terms of the kinetic energy of the particle bombarding the growing film. Measurements of the chemical composition show that In to Sb concentration ratio increases with the increase of working pressure because Sb atoms are more rapidly thermalized by collisions with argon atoms during the transport process of the sputtered atoms. And the composition of the films is governed by the Sb re-evaporation process at the surface of the growing films. In to Sb concentration ratio is enhanced by increasing the substrate temperature (essentially) or RF power.

A novel process of micro-arc oxidation (MAO) on AZ91D magnesium alloy is investigated in a Na2SiO3-NaOH-montmorillonite-EDTA-acacia gum electrolyte solution. The morphologies, elements distribution, phase components of the coatings are characterized by SEM, EDS and XRD. And CHI600 electrochemistry corrosion workstation is employed to investigate the property of corrosion resistance of the coatings. Furthermore, the anti-corrosion behavior is analyzed immersed in 3.5 wt. % NaCl solution. The results reveal that the ceramic coatings have the relatively dense and uniform in thickness and the silicon element tends to present primarily in the outer region of the coatings. The XRD results indicate that the oxide films are mainly composed of Mg2SiO4 and MgAl2O4 phases. The immersion results show that the corrosion resistances of the ceramic coatings on AZ91D magnesium surface are better than the magnesium substrate.

The doped and non-doped white Organic light-emitting devices (OLEDs) were fabricated, using strong yellow emitting and hole-transporting ability of TPAHQZn. When the white OLED is a double-doped structure, greatly enhanced the efficiency of the device. The double-doped white device were fabricated as follows: ITO/2T-NATA (17 nm)/ CBP: 30% TPAHQZn: 8% Ir(ppy)3 (25 nm)/ NPBX (15 nm)/BCP(8nm)/TPBi: 10% Ir(ppy)3 (15nm)/Alq3 (20 nm)/LiF (1.3 nm)/Al. The double-doped white OLEDs were obtained with Commission International de L’Eclairage coordinates of (0.29,0.28) at 17 V, the maximum current efficiency increaed four times that double-doped white device of 4.12cd/A(8V) than non-doped of 1.03 cd/A (10V) .

The influence of five variables (i.e. deposition temperature, time, bath pH, and concentrations of Cr3+ compound (KCr(SO4)2) and H3PO4) on the preparation of Cr3+ coating on Al 6063 alloy was investigated using AC impedance spectroscopy (EIS) in 3.5 wt% NaCl. The optimal conditions were determined by AC impedance spectroscopy. The results indicated that the formation and quality of the coating were very sensitive to the deposition bath pH. A mechanism was proposed to explain the results. A simple model was derived and experimentally tested in terms of an equivalent circuit. Good agreement was found between the model predictions and the experimental results. The morphologies of the coated and uncoated electrodes were examined by scanning electron microscopy (SEM), and the results also support the proposed surface model.

We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4′-bis(2,2-diphenyl vinyl)-1,1′ — biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/ NPBX (20 nm)/ CBP: x%Ir(ppy)3:0.5% rubrene (8 nm)/ NPBX (5 nm)/DPVBi (30 nm)/ Alq(30 nm)/LiF(0.5 nm)/Al. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3], acts as a yellow light-emitting layer, and N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1, 1′-biphenyl-4,4′-diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (ppy)3 is 6wt%, the maximum luminance is 24960 cd/m2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.

The electron beam could be controlled by magnetic field for fast deflection, in which way multi-beam could be produced by deflection technique. The multi-beams run simultaneously for material processing with different heat input and positions. Therefore, it is possible to adjust the thermal effects and optimize the process. In this paper, the generation of multi-beams in electron beam welding (EBW) was investigated, and the processes of EBW with multi-beams were also investigated by both the numerical simulation methods, i.e., finite element analysis (FEA), and the experiments. The result shows that the residual stress of EBW could be minimized by using the multiple beam technique, and at the same time the welding deformation could also be reduced with the optimized parameters.

Chromium (Cr3+) conversion coating was prepared on 6063 aluminium alloy using chromic potassium sulfate and phosphoric acid. Tafel polarization curves and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of the coating formed under different conditions. The optimum conditions were obtained as following: temperature was 30-40 ℃, deposition time 9 min, the pH was adjusted to 2.0-3.0, the KCr(SO4)2 and H3PO4 concentrations were controlled within 15-25 g·L-1 and 10-20 g·L-1, respectively. The polarization result showed that the coating had more positive corrosion potential (Ecorr) and pitting corrosion potential (Epit), and lower corrosion current density (icorr), indicating that the coating formed under the optimum conditions had better corrosion resistance. To explain the electrochemical properties of the coating, a simple equivalent circuit was designed. Electrochemical parameters of EIS, such as the resistance (Rcoat) and capacitance (Ccoat), the charge transfer resistance (Rct) and double layer capacitance (Cdl), were obtained by fitting the EIS plots. The results of EIS were in good agreement with those of Tafel polarization curves.

Highly efficient white phosphorescent organic light-emitting devices (WOLEDs) was fabricated using an electron/exciton blocker. The device structure is ITO/2T-NATA(25 nm)/ NPBX(25-dnm)/CBP:5%Ir(ppy)3:0.5%Rubrene(8 nm)/NPBX(dnm)/DPVBi(30 nm)/TPBi(20 nm)/Alq(10nm)/LiF(1nm)/Al, in which N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1, 1′-biphenyl-4,4′-diamine (NPBX) functions as a hole transport layer and electron/exciton blocker, 4,4,N,N′-dicarbazolebiphenyl (CBP) is host, 4,4′-bis(2,2-diphenyl vinyl)-1,1′-biphenyl (DPVBi) is blue fluorescent dye, 5,6,11,12,-tetraphenylnaphthacene (rubrene) is fluorescent dye, factris (2-phenylpyridine) iridium (Ir(ppy)3) is phosphorescent sensitizer and tris(8-hydroxyquinoline) aluminum (Alq3) is an electron transport layer. The WOLEDs have obtained white light emission by adjusting the thickness of NPBX, when the concentration of Ir(ppy)3 is 5-wt% and rubrene is 0.5-wt%, respectively, the thickness of the doped emissive layer is 8 nm, the WOLEDs show a maximum luminous efficiency is 11.2 cd/A with d of 10 nm at 7 V and a maximum luminance of 28170 cd/m2 at 17 V, the CIE coordinates is (0.37.0.42), which is in white region.

Electron beam surfi-sculpt is a novel surface processing technology,in which electron beam is controlled by magnetic field and deflected quickly over a substrate surface to displace materials in a settled manner,thus producing customized textured surface consisting of an array of protrusions above the original surface and a corresponding array of cavities in the substrate.This technology could be used in dissimilar materials connection between metals and composites,as the protrusions on metal surface would increase the interface area,which results in great improvements in both strength and absorbed energy.It could also be applied to improve the surface coating quality by tailor-making protrusions throughout a component surface so as to enhance the adhesive capacity between coating and substrate,as well as to optimize the stress distribution that occurs in coating process.The application performance of textured surface depends on the microstructure characterisation of protrusions,while the investigation on the microstructures and mechanical properties of the protrusion is lack.In this work,electron beam surfi-sculpt was carried out to produce protrusions on TA15(Ti-6Al-2Zr-1Mo-1V) surface through multi-beam technique. The microstructure features of protrusions were investigated by OM,SEM and XRD,and the weight percentages of alloy elements were analyzed by EDS.In addition,the micro-hardness of the four zones were measured and the results were explained by its microstructure features and weight percentages of alloy elements.It was found that four zones exist in the protrusion,namely edge zone,central zone, heat affected zone(HAZ) and substrate.The edge zone is composed of coarse grain with platelet martensite inside,whose micro-hardness is the lowest.The central zone,whose micro-hardness is the second lowest,is constituted of coarse grain with regular-layed platelet martensite;however,the grain size is smaller than that in the edge zone.The HAZ is characterized of fine grain with boundaryαand parallel-layed short platelet martensite inside,plus the highest micro-hardness.The weight percentages of Al in the HAZ and the substrate were higher than that in the edge zone and the central zone,which,together with different grain size of the four zones,are the two main reasons for the micro-hardness differences of the four zones.