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利用锂钙硼玻璃在磷酸盐溶液中的原位转化反应制备表面多孔的中空羟基磷灰石(HAP)微球。通过扫描电镜(SEM)、电子能谱(SEM-EDS)、X射线衍射(XRD)仪、和红外光谱(FTIR)仪分析微球的形貌和物相,研究与探讨中空HAP微球的形成与转化机制。结果表明:所制备的微球具有良好的中空结构;中空微球物相为包含B型碳酸根的缺钙羟基磷灰石,具有仿生性。600 ℃热处理后,微球球壳完全由包含碳酸根的缺钙羟基磷灰石晶体组成,并显示出一定的机械强度。在磷酸盐溶液中,锂钙硼玻璃表面原位生成Ca-P-OH水化物,并在玻璃表面原来Ca2+的位置沉积下来,形成微球壳,而由Li+和B3+占据的位置,因其溶出形成孔隙。这样的结构将有利于制备表面多孔的中空羟基磷灰石多孔贮库型药物释放系统的载体 相似文献
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羟基磷灰石由于其良好的生物活性,被广泛的用作医用植入体的表面涂层材料.采用微束等离子喷涂(Microplasma Spraying,MPS)I艺在Ti-6Al-4V基体上制备羟基磷灰石涂层,通过扫描电镜(SEM)、X射线衍射(XRD)和傅里叶红外光谱(FTIR)分析了热处理对涂层相组成和表面形貌的影响规律.研究表明:微束等离子喷涂制备的羟基磷灰石涂层在经过热处理后结晶度提高,并且非晶相和杂质相转化成为HA结晶相.同时,羟基和磷酸根的完整性得到了恢复.过高的热处理温度易引起涂层裂纹等缺陷的增加,也容易造成羟基脱离造成HA分解.合理的热处理温度范围为600~700℃,保温时间为3 h. 相似文献
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用粉末冶金法制备Ni-Fe-Al合金,将元素Ni、Fe、Al粉混合后在500 MPa的压力下进行压制成形,分别在1280 ℃和1300℃下进行烧结,对烧结坯进行密度、拉伸力学性能检测、X射线衍射分析、断口及组织观察.结果表明,在1280 ℃烧结时NiFe18.5Al25合金密度可达6.57 g/cm3(相对密度为94.3%),抗拉强度达到718.7 MPa,说明采用粉末冶金法可制备高性能Ni-Fe-Al合金.烧结Ni-Fe-Al合金中γ相的体积分数随Ni含量增加而增加,相对密度和抗拉强度随Ni含量的增加而提高,说明γ相的增加有利于烧结.对比三种合金,NiFe18.5Al25合金性能最优,主要是由于该合金中γ相体积分数最高. 相似文献
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用粉末冶金技术制备Ni56Fe19Al25合金,将Ni、Fe、Al的元素粉与预合金粉等量混合后在500 MPa下压制成形,于1280 ℃温度烧结后进行热处理,对合金烧结态和淬火态进行X射线衍射(XRD)分析及力学性能检测。结果表明:粉末冶金技术制备的Ni56Fe19Al25合金烧结态为(β+γ)双相组织,淬火态处于(β′+γ)双相区。Ni56Fe19Al25合金淬火态在应力作用下呈现出良好的线性超弹性,抗拉强度达850 MPa,最高弹性变形量大于4.5%,断裂前总变形量达到9.2%。 相似文献
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通过两步湿化学沉淀法,在AZ31镁合金表面制备了聚多巴胺/羟基磷灰石复合涂层。使用扫描电子显微镜 (SEM),原子力显微镜 (AFM),X射线光电子能谱 (XPS),X射线衍射仪 (XRD) 及傅里叶红外仪 (FT-IR) 等表征了样品的形貌及结构。结果表明,聚多巴胺膜层平滑致密,经聚多巴胺诱导沉积的羟基磷灰石膜为交错排列的片状羟基磷灰石垂直阵列。利用电化学极化曲线和阻抗谱表征了聚多巴胺/羟基磷灰石复合膜的耐蚀性能,结果显示复合膜使AZ31镁合金在SBF溶液中的耐腐蚀性能明显提高。 相似文献
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为了改善镧镁镍贮氢合金的循环稳定性,以La0.78Mg0.22Ni3.70合金为研究对象探索放电等离子烧结适宜温度。采用扫描电镜(SEM)、X射线衍射(XRD)分析了合金的断口形貌及相结构,电池测试仪测试了合金的电化学性能。结果表明,合金的烧结过程含有膨胀—收缩阶段,收缩阶段相对较长。随烧结温度升高,合金收缩引起的位移增加,合金断口先致密后蓬松,含有LaNi5、(La,Mg)2Ni7主相以及LaNi2.28残余相。与其它温度烧结合金相比,950℃烧结合金具有较高的放电容量和循环稳定性。 相似文献
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采用微束等离子喷涂方法,在Ti-6Al-4V基体上制备了羟基磷灰石 氧化锆(70HA-30ZrO2,质量分数,%)复合涂层.将复合涂层置于模拟体液中分别浸泡了3,7,14,28 d并观察表面磷灰石的生长情况以评价涂层生物活性.采用扫描电镜(SEM)和X射线衍射(XRD)分析技术对涂层浸泡前后的表面形貌和相组成进行了研究.结果表明,涂层中ZrO2主要以立方相存在;喷涂过程中羟基磷灰石(HA)出现了一定的分解,产生大量的α-Ca3(PO4)2杂质相.HA涂层熔化效果很好,但涂层中有未熔化的ZrO2颗粒.涂层在模拟体液中浸泡28 d后表面可以形成磷灰石,说明涂层具有很好的生物活性. 相似文献
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粉末冶金Ti-Al-Mo-V-Ag合金的显微组织与力学性能 总被引:1,自引:0,他引:1
通过粉末冶金元素混合法,制备含α及β相的Ti-Al-Mo-V-Ag合金。通过X射线衍射、金相观察、扫描电镜观察及力学性能测试,研究Ag的添加及烧结温度对Ti-5Al-4Mo-4V合金的组织与性能影响。结果表明:Ag的添加能提高粉末冶金Ti-5Al-4Mo-4V合金的的相对密度,改善合金的力学性能;在1250℃下烧结4h后,Ti-5Al-4Mo-4V-5Ag合金的相对密度及抗压缩强度分别达到96.3%和1656MPa。 相似文献
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Tatsuo Ishikawa Kumi Matsumoto Kazuhiko Kandori Takayuki Tsubota 《Corrosion Science》2004,46(2):329-342
The artificial rust particles were prepared from ZnCl2 solutions dissolving Al(III), Fe(III), Fe(II), Ni(II), Co(II) and Mg(II) at different atomic ratios from 0 to 0.3 in metal/Zn. With increasing metal/Zn the crystal phases of the products turned following as ZnO → a mixture of ZnO and Zn5(OH)8Cl2 · H2O (ZHC) → ZHC. Al(III) most facilitated the formation of ZHC but Mg(II) and Fe(III) produced no ZHC. The morphology of the formed particles varied following as agglomerate → fine → rod → sheet → irregular with the increase of metal/Zn. The sheet and irregularly shaped particles were identified as ZHC and the other particles as ZnO. 相似文献
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Effect of solution heat treatment on galvanic coupling between intermetallics and matrix in AA7075-T6 总被引:1,自引:0,他引:1
Susceptibility to localised corrosion is strongly affected by heat treatments performed on Al-Zn-Cu-Mg alloys. In order to study how galvanic coupling between intermetallics and matrix is affected by solution heat treatment, AA7075-T6 and solution heat treated AA7075 have been characterised by means of scanning electron microscopy and scanning Kelvin probe force microscopy. Solution heat treatment strongly increased the Volta potential difference between the intermetallics and the surrounding matrix showing a strong increase in galvanic coupling. This is explained by Zn and Mg enrichment of the matrix caused by dissolution of strengthening particles during solution heat treatment. 相似文献
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Effect of dislocation density on the low temperature aging behavior of an ultra low carbon bake hardening steel 总被引:3,自引:0,他引:3
A. K. De K. De Blauwe S. Vandeputte B. C. De Cooman 《Journal of Alloys and Compounds》2000,310(1-2):405-410
Strain aging was studied in an ultra low carbon (ULC) steel with a total carbon content of 20 ppm (wt.%) in order to identify the process stages and mechanism of bake hardening in this type of steel. The effects of dislocation density, varied by means of uniaxial tensile prestraining (1–10%) on the aging kinetics were investigated within an aging temperature range of 50–170°C. The aging was evaluated by means of strength measurements and the determination of interstitial carbon content after aging using a piezoelectric composite oscillator operating at 40 kHz. The interaction between interstitial carbon and dislocations was examined through amplitude dependent internal friction measurements. The influence of dislocation density on the aging behavior have been discussed with reference to the kinetics and mechanism of the aging process. 相似文献
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AC and DC electrochemical experiments were performed as a function of humidity and contaminant concentration in an effort to identify the range of atmospheric environments where corrosion processes could be detected and possibly quantified. AC measurements exhibited two time constants at 25% relative humidity (RH), possibly indicating the ability to resolve both electrolyte resistance and interfacial impedance. Galvanic current measurements were sensitive to the presence of Cl2(g) at 30% RH and electrochemical transients were detected at both 30% and 50% RH levels, also indicating sensitivity to interfacial processes. Higher humidity levels allowed better quantification due to decreasing electrolyte and interfacial impedances. 相似文献
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The corrosion behaviour of melt spun amorphous and nanoquasicrystalline Zr70Pd30 and Zr80Pt20 alloy ribbons has been investigated using potentiodynamic polarization study in NaCl, H2SO4 and NaOH solutions at different concentrations. The amorphous and nanoquasicrystalline alloys show better corrosion resistance than Zr in all the solutions studied. Both the alloys are susceptible to chloride attack and pitting has been observed. Complete passivation has been observed in H2SO4, while gradual break down of passivating layer occurs in NaOH. In general, nanoquasicrystalline state in both the alloys shows better corrosion resistance than amorphous state in all the solutions studied. 相似文献
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The deactivation of an IrO2–Ta2O5 coated titanium anode was studied during an accelerated life test at 2 A cm−2 in 1 mol dm−3 H2SO4 solution using CV, EIS, SEM and EDX. The changes of voltammetric charge, double layer capacitance, oxide film resistance and charge transfer resistance of oxygen evolution with time during the electrolysis were monitored. The morphology and surface composition of the oxide anode before and after electrolysis test were analysed. A comprehensive process of deactivation of the oxide anode was proposed based on the test results and analysis. 相似文献
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A.V Sameljuk 《Corrosion Science》2004,46(1):147-158
The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion. 相似文献
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The performance of three imidazoline-like inhibitors in CO2 corrosion was studied by means of electrochemical measurements employing a.c. and d.c. techniques. Carbon steel with two different microstructures (annealed, and quenched and tempered (Q&T)) was used in a deoxygenated 5% wt. NaCl solution, saturated with CO2 at 40 °C and pH 6. Aminopropylimidazol (API) and two commercial imidazoline-based products (PC and QB) were used as inhibitors. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LRP) studies showed that the annealed samples have a better corrosion resistance than the Q&T samples when API and PC were added. On the other hand, the presence of QB yielded the opposite results. From the Bode phase angle plots it can be concluded that in the first case and for both microstructural conditions, there is no indication of formation of an inhibitor film, whereas in the presence of QB its formation is clearly evident. Based on these experimental findings, a mechanism of action for each inhibitor is proposed. 相似文献