Effect of heat treatment on microstructures..

 1 Experimental

    1.1 Preparation of samples of titanium anodeTA2 pure titanium as the anode to the substrate, raw materials used in the experimentRuCl3,(C4H9O)4Ti, H2IrCl6?6H2O(w(Ir)=34.9%),TaCl5, ethanol, butanol. According to a representative of the coatingStoichiometry of metal elements, n(Ru): n(Ti)=3:7, n(Ir): n(Ta)=7:3,

    3And(C4H9O)4Ti with ethanol as solvent, H2IrCl66H2O and?TaCl5 with butanol as the solvent, and then two kinds of coating liquid mixture, to obtainRu-Ti-Ir-Ta coating solution quaternary. Quaternary coating solution coated on the surface of titanium substrateSpecific process, see[12], the titanium anode were500¡æ and700¡æSintering, respectively, after annealing1 h with furnace cooling to room temperature, in order to obtainTitanium anode samples.

    1.2 DetectionCoating phase analysis test Shimadzu XB-5A-type X-rayDiffractometer. Test conditions: Cu target K¦Á(¦Ë=1.5406?),

  Fe filter, accelerating voltage35 kV, tube current20 mA, scanning speed

    min, step1. Estimated using the formula Schrerrer coating(101)Crystal face of the grain size.Microscopic morphology of coating surface using scanning electron Japan JSM6700FChild microscope. Voltage of10 kV in the work observed; random broughtThe JSM6700F-type X-ray spectrum analyzer, the working voltage20 kVUnder the micro-area composition were characterized.For the coating of the grain shape and size of the Japanese TecnaiG2 F20 high-resolution transmission electron microscope under an accelerating voltage of200 kVBe. File using the mechanical method scraping the surface of coated samples collected peel powder,Dispersed in ethanol, made from powder coated suspension. Ultrasonic shockSwing30 min, the coating powder dispersed. Take drop in a special solutionMicro-grid on the dried samples obtained by HRTEM. www.hzbst.com

    2 Results and discussion

    2.1 Organization of temperature on the coating of the phaseFigure1 shows the annealing at different temperature XRD of titanium anodeSpectrum. Figure1(a) can clearly see the different treatment of the anode temperatureXRD coating is basically the same position of the three strong peaks, the spacing and TiO2Rutile standard card corresponding d values3.247,2.487,1.6874?Closer comparison. And because Ti(0.075 nm), Ru(0.076 nm),Ir4+(0.077 nm) very close to the ionic radius and oxidation of the threeMaterials were rutile crystal structure[13], relatively easy to form betweenSolid solution, it can initially determine, at500¡æ and700¡æ backFire titanium anode coatings are mainly composed of rutile phase solid solution.According to ion size difference between the15% of the rules relative to Ti, RuAnd Ir-based oxides can be formed between two infinite solid solution, butThe study found that treatment at different temperatures of the anode coating XRDDiffraction peaks are not rules. To further understand the phases ofThe second peak is strong(101) plane diffraction peak of further decomposition, the ResultsResults shown in Figure1(b) below. Annealing at500¡æ, the composition is two-

    101Ir-based(Ir, Ti, Ru) O2 and Ti-based(Ti, Ru, Ir) O2 rutile solid solutionBody. Analysis using linear profile, we can see,(Ir, Ti, Ru) O2 GoldRedstone about36% solid solution and grain size larger,(Ti, Ru, Ir) O2About64% rutile solid solution, and the grain size small. BySchrerrer calculated two-phase grain sizes are15 nm and

    8 nm. RuO2 not found in the map the peaks, it is becauseBetween the radius of Ru and Ti, between Ir, when the annealing temperatureAt500¡æ, Ru4+ as a replacement ion dissolved in Ti-based and Ir-based solid solutionIn. When the annealing temperature to700¡æ, the coating phase is composed of three-phase,d101 values were respectively, close to the IrO2Rutile, RuO2 rutile, TiO2 rutile standard card correspondingWith the annealing temperature(101) plane diffraction peak area found that when the annealing temperatureDegree is700¡æ, the area surrounded by peaks over500¡æ, large,Help rutile coating increases the total content of solid solution phase.Ta2O5 are not found in the map the peaks, indicating that most of theTa elements are coated in amorphous form.[15] showed thatTo observe the characteristic peaks of Ta2O5, the sintering temperature higher than600¡æ.In this study, the sintering temperature of700¡æ, although higher than the temperature,But it does not appear Ta2O5, which may be affected by coating other metal elementElements of the results. In addition, the pattern seen in both the derivative Ti-basedRadio peak, because the coating thickness is thinner, not enough to stop the X-rayPenetration. Careful observation can also be found under the conditions of700¡æ annealingTi-based diffraction peak intensity is lower than that at500¡æ annealing conditions, whichMay be due to the higher annealing temperature causes the surface of Ti was partially based oxygenOf the reason.

Temperature on the microstructure morphology of coating surface
Annealed anodic coating surface morphology shown in Figure 2. When the Ru-Ti-Ir-Ta oxide anode quad at 500 ℃ and 700 ℃ annealing
Annealing temperature of 500 ℃, the coating surface roughness, showing the typical "mud cracks
Like "(see Figure 2 (a)), was double-coated structure (see Figure 2 (b)), appears a
Times cracks and secondary cracks [16]. A crack is already in the drying process
Existing, secondary cracks are generated during heat treatment, all the turtles
Split block smooth surface, the size of individual cracks in a small block
Particle concentration, but the small number of particles concentration, and no clear analysis of the XRD spectra after

Fig.1 XRD patterns of Ru-Ti-Ir-Ta quaternary oxide titanium
anodes after being annealed at 500 ℃ and 700 ℃
d101 values 2.582,2.550,2.530 Å, which can be considered in the map
Ir appears that the base (Ir, Ti, Ru) O2, Ru-based (Ru, Ti, Ir,) O2,
2
Ru4 + solution and the radius of the smaller capacity of Ti4 + and not at 700 ℃
Weakened, Ir-based (Ir, Ti, Ru) O2 rutile solid solution continues to grow,
Diffraction peaks increased. Ru from the larger ionic radius of Ti-based (Ti, Ru,
2
Ru-based solid solution phase shows a linear profile, Ti solubility in which to
Higher than that in which the solubility of Ir. Because the same amount of coating material,
For these reasons, Ti-based solid solution decreases, diffraction peaks decreased,
3 phase rutile solid solution, Ru-based solid solution phase content is less, only about 4%
Ir-based and Ti-based solid solution phase were 52% and 44%. By Schrerrer
Ir-based formula, Ru and Ti-based solid solution phase of the grain Redstone Fund
Size were 18,29 and 12 nm. Comparison of the grain solid solution phase 3
Size that although the Ru-based (Ru, Ti, Ir,) O2 solid solution appears more
Late, but fast grain growth, grain size and even more than the Ir-based
Ti-based solid solution grain size. According to the literature [14] introduced, when the sintering temperature
Degrees higher than 600 ℃,, RuO2 rutile grew faster. Less
[12]
Out. High magnification observation of a deep crack crack, you can see a large
Precipitation of small particles of different particle size of less than 80 nm (see Figure
2 (c))
Is the (Ir, Ti, Ru) O2 rutile solid solution, which is to improve titanium anodes
Electrochemical stability and electrocatalytic activity are very favorable.
When annealed at 700 ℃, still on the anode surface morphology
"Mud crack-like" coating multilayer structure, a crack appeared, two
Second crack and three cracks. Causes of a crack under the impact of crack
The width of lines and shapes with 500 ℃ formed under similar conditions. II
Three times crack and crack is formed during heat treatment, with the heat
Processing temperature, the secondary cracks deeper, wider, crack the block surface
Relatively large volume. Three cracks at the surface of the second crack, crack block
The central part of the still smooth, but there are slightly at the edge of a sense of the crack (see Figure
2 (d)). Cracks at the secondary cracks, the cracks appeared more uniform blocks of size
Distribution which, at the same time, the edge of the secondary cracks are more and more
Ru-based (Ru, Ti, Ir) O2 and Ir-based (Ir, Ti, Ru) O2 rutile solid
Solution takes the shape of granular precipitates (Figure 2 (e)). The high magnification observation, which
These precipitates vary in size, but the shape is similar to the precipitation of particulate matter
Larger size (see Figure 2 (f)). Active component of the precipitation, on the one hand can provide
Titanium Anodes with high activity, but also because of significant precipitation particles,
Reduced resistance to gas erosion resistance and easy to fall off from the coating surface, resulting in enhanced
Reduced life expectancy.

 Fig.2Ru-Ti-Ir-Ta oxide anode quad at500¡æ and700¡æ SEM image after annealingSEM images of Ru-Ti-Ir-Ta quaternary oxide titanium anodes annealed at different temperatures:(a),(b),(c)500¡æ;(d),(E),(f)700¡æ

    2.3On distribution of temperature on the impact of coating groupTo further analyze the distribution of anode surface condition of each element of2Rutile solid solution mainly in the crack surface area is2, and Ru-based(Ru, Ti, Ir) O2 and Ir-based(Ir, Ti, Ru) O2 rutile solid solution

    EDX analysis of types of anodic coatings. At500¡æ, the coatingDifferent regions of Ru, Ti, Ir, Ta mole fraction of four metalsNo significant change in the number of[12]; treatment at700¡æ, in different regionsMole fraction of the metal elements are significantly different.Table1 lists indicated in Figure2 of the micro-coating the metal surfaceMole fraction of element specific data. Table1 shows that at500¡æSintering, the element Ti was significantly higher than the element of the mole fraction of Ru and Ir, andTi oxide coating that is mainly based(Ti, Ru, Ir) O2 rutile solid solutionBody, Ta elements in the anode coating evenly. Sintered at700¡æTime, Ti elements in Zone2, Area3, the mole fraction higher than about38%; andIn contrast, Ru and Ir elements in the two areas less than3 mole fraction region,

    24% lower, respectively, and23%. Can be judged accordingly, Ti-based(Ti, Ru, Ir) O2[14-15]

    In the form of segregation Zeyi edge crack that precipitation in Region3. Research

    Produce segregation, this may be due to the formation of rutile in the3 phase can beMetal ions, Ir4+ and the larger the radius of Ru4+, Ti4+ radius of the smallest

    2Lattice expansion caused by the large lattice distortion, which is bound to the phase of theNegative impact on the thermal stability. Ta element distribution in the two regionsAlso significantly different from Zone2 Zone3 with Ta content is2 times. As Ta4+Large size, the precipitation of the Ru-based segregation and Ir-based solid solution, TaElements not easily dissolved. It can be that most of the Ta elements areDistributed in the form of amorphous coating the surface of the anode.

    TableIndicated in Figure2 in the coating micro-EDX analysis of metal elements

    1 EDX results of metal elements in coating inCoating(see Figure3(b)) the grain size of8~18 nm, the grain size of individualGreater than25 nm, it is clear, which is based Ru(Ru, Ti, Ir) O2 GoldFig.2(mole fraction,%)Zone Ti

    160

    261

    323

    1-500¡æ;2-700¡æ:3-700¡æRu

    18

    15

    39Ta

    13

    15

    7Ir

    9

    9

    31Redstone solid solution content is less relevant. It can be seen, different annealing conditionsRutile solid solution phase under mostly equiaxed grain morphology are dominated, but the700¡æ, the grain coarsened.

 Conclusion

2.4
High-resolution transmission electron microscopy coating observations
By transmission electron microscopy of different temperature treatment
1) with different temperature treatment of Ru-Ti-Ir-Ta quaternary metal oxide
Titanium anode material coating, 500 ℃ of the coating is mainly composed of Ti-based phase
Ru-Ti-Ir-Ta quaternary metal oxide coated titanium anode microstructure characteristics
Sign shown in Figure 3, field of vision, different temperatures of rutile coating
Solid solution phase are equiaxed grain based. Can be seen from Figure 3, after 500 ℃
Treated coating (see Figure 3 (a)) the grain size of 3 ~ 10 nm, not seen
[12] described a multi-type characteristics of the columnar crystal, which is due to
This was characterized for the Ir-based (Ir, Ti, Ru) O2 rutile solid solution
The content of the coating very small proportion of the reason; treated at 700 ℃
(Ti, Ru, Ir) O2 and Ir-based (Ir, Ti, Ru,) O2 rutile solid solution;
Replacement of Ru element mainly existed in the two solid solution,
Ta amorphous form element Zeyi coating. Ti-based (Ti, Ru,
Ir) O2 and Ir-based (Ir, Ti, Ru) O2 rutile solid solution was the main grain
Equiaxed morphology, and their grain sizes are about 15 nm and 8 nm.
Coating surface morphology was typical of the "mud crack-like" characteristics, the surface of the coating
Is a crack and the second crack, the crack pieces smooth surface, in the
Crack the bottom of the distribution of a small amount of Ir-based (Ir, Ti, Ru) O2 Jinhong
Rock solid solution aggregates.
2) 700 ℃ phase in the coating composition of Ir-based (Ir, Ti, Ru) O2,
Ti-based (Ti, Ru, Ir) O2 and Ru-based (Ru, Ti, Ir) O2 rutile solid
Melt-based, and their grain sizes were about 18,29 and 12 nm,
3 solid solution phase showed equiaxed grain morphology. Coating the surface with a "mud cracks
Like "feature, showing a multi-level structure, secondary cracks deeper, wider and cracking
Larger blocks, at the crack, the crack pieces with uniform size distribution of which
Cracks appeared in the block three times the surface cracks. Micro-components analysis, Ru
Base (Ru, Ti, Ir) O2 and Ir-based (Ir, Ti, Ru) O2 rutile solid solution
Imposed at the crack edge of the precipitation in the form of segregation, indicating that high temperature treatment
When significant precipitation phenomenon.