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Abstract:Possessing multiple energy levels, unique 4f electron transition ability and optical properties, rare earth elements can improve efficiently the activity of TiO2 photocatalysts by doping or preparing compound semiconductors. Furthermore, novel photocatalysts have been secured with RE elements. Based on relative documents, the application of rare earth elements in photocatalysts is reviewed in this paper, including RE modified TiO2 photocatalysts and non-TiO2 photocatalysts. The roles of RE elements and its mechanism, as well as the focus and outlook of the research of RE-containing photocatalysts were deeply discussed.

Abstract:Bulk metallic glasses have unique mechanical properties, including high strengths (~2 GPa), large elastic limits (2%~3%), and excellent resistance to corrosion, but the poor room temperature ductility restricts its applications as structural materials. In this paper, the room temperature brittleness of bulk metallic glasses was discussed based on the deformation and fracture mechanism, and the progress in improving room temperature ductility by introducing second phase in the amorphous matrix was summarized.

Abstract:REO-ZrO2 mixed oxides serve as a key material in the electrolyte of oxygen sensor and promoter of three-way catalyst (TWC), which are widely applied in the purification of automotive exhaust. The principles of the applications were expounded; meanwhile the adulteration of RE ions into ZrO2 applied in oxygen sensor was introduced. The research of CeO2-ZrO2 mixed oxides applied as promoter of TWC was summarized, and the further application of REO-ZrO2 composite in the automotive exhaust decontamination was prospected.

Abstract:Three-dimensional (3D) C/SiC composites with a CVD SiC coatings and a PyC interphase were prepared by low-pressure chemical vapor deposition method. The interphase was annealed and changed in thickness. Dualism, certainty and randomicity, in the evolution of C/SiC composites under complicated environments were investigated. The results show that residual strength and its fluctuation are important when evaluating environmental adaptability and reliability. The interphase and coatings are the key microstructural units most sensitive to oxidizing environments. The three parameters to be considered, in order of importance, are temperature, atmosphere and stress sensitivity. The most significant atmosphere is oxygen, followed by water and salt, while the most important stress parameters are fatigue/creep interaction, creep and fatigue. Stress promotes degradation of the composites due to opening of cracks in the coatings. An oxide film on the coatings is best to seal these cracks, and water can accelerate this sealing. However, a fatigue/creep interaction stress causes sealing failure, and then the environment including oxygen, water, fatigue and creep is the worse one of all. For the composites to be self-adaptable, the PyC thickness should be optimum for increasing annealing effect, and the coatings should be oxidized at a moderate rate for increasing resistance to oxidation. The temperature and the partial pressure of oxidizing gases control the moderate rate.

Abstract:采用電化學(xué)測(cè)試技術(shù)研究了在PBS人工模擬體液中纖維蛋白原對(duì)CoCrNiMo和CoCrNiW合金腐蝕行為的影響.結(jié)果表明,CoCrNi合金具有良好的耐孔蝕性能,其鈍化電位區(qū)較寬,且電位掃描曲線滯后環(huán)面積小.用EDX能譜對(duì)試樣進(jìn)行分析發(fā)現(xiàn),在CoCrNi合金表面形成了Co,Cr,Ni,Mo,W等的鈍性金屬氧化物膜.纖維蛋白原在CoCrNi合金表面發(fā)生了吸附,且吸附的蛋白質(zhì)分布不連續(xù).用紫外吸收法測(cè)量CoCrNiMo和CoCrNiW對(duì)纖維蛋白原的吸附量分別為10.628 μg/cm2和9.561μg/cm2.含有纖維蛋白原的PBS人工模擬體液中CoCrNi合金的腐蝕行為可用吸附理論解釋.其反應(yīng)步驟為(1)氧原子吸附在合金能量較高的活性點(diǎn)上,形成較為穩(wěn)定的吸附氧化膜;(2)纖維蛋白原擴(kuò)散到合金表面以形成絡(luò)合物的形式與氧原子構(gòu)成競(jìng)爭(zhēng)吸附;(3)形成的金屬絡(luò)合物向溶液產(chǎn)生電化學(xué)遷移,破壞了合金表面的鈍性氧化膜,使icorr值顯著增大,加劇了合金的腐蝕.

Abstract:The XRD, SEM, isothermal oxidation-weight loss and non-isothermal TG-DTG were used to study the properties of SiC coatings/ 3-D braided carbon fiber(composite fiber) prepared by in-situ reaction method. The results show that coatings is coated symmetrically and combine well with every fiber of 3-D braids in proper reaction conditions, the oxidation resistance of composite fiber increase with the increase of SiC coatings thickness. The oxidation resistant properties and mechanism of composite fiber were studied also.

Abstract:The plastic deformation during quenching is first induced by tension stress, and then alternative occurrence of tension and compression stress induce plastic deformation. The tension stress may induce compression stress. Compression stress occur in the surface, which is different from conventional view that only tension stress occurs in the surface. The thermal stress during quenching is mainly determined by temperature difference other than temperature. Compression stress occur and develop in the relative high temperature zone, and tension stress occur and develop in the relative low temperature zone. It is the source of thermal stresses, plastic deformation, residual stresses when quenching or quickly heating. The corner and edge models for thermal stress during quenching are established in this paper, and the corner effect, which go with the recession of, temperature grads, thermal stresses and plastic deformation after the first plastic deformation is induced by tension stress, is proposed in the course of quenching.

Abstract:用脈沖激光沉積法在斜切(001)SrTiO3單晶基片上生長(zhǎng)了c軸取向的YBa2Cu3O7-δ超導(dǎo)薄膜,在斜切(001)LaAlO3單晶基片上生長(zhǎng)了Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ雙層薄膜,并用掃描電鏡和透射電鏡對(duì)薄膜組織進(jìn)行了表征。結(jié)果表明,在1°~3°斜切的SrTiO3基片上生長(zhǎng)的YBa2Cu3O7-δ薄膜,呈現(xiàn)臺(tái)階流動(dòng)(stepflow)到三維島狀生長(zhǎng)的轉(zhuǎn)變;而6°~15°斜切基片上生長(zhǎng)的YBa2Cu3O7-δ薄膜為完全臺(tái)階流動(dòng)生長(zhǎng)。在1.2°斜切的LaAlO3基片上原位制備了良好異質(zhì)外延生長(zhǎng)的Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ雙層薄膜。在77K,1MHz頻率和±30V直流偏壓下,測(cè)定了其電容-電壓特性,確定其介電常數(shù)、可調(diào)諧性和品質(zhì)因數(shù)分別為1200,60%和133。表明該Ba0.1Sr0.9TiO3薄膜可應(yīng)用于在液氮溫度下工作的可調(diào)諧微波器件。

Abstract:以乙酰丙酮鉑為前驅(qū)體,采用金屬有機(jī)化合物化學(xué)氣相沉積(MOCVD)法在石英及YSZ基體上制備Pt/C薄膜,研究了Pt/C薄膜的結(jié)構(gòu)和電化學(xué)性能。沉積過(guò)程中通入一定量的氧氣可以大幅降低Pt/C薄膜中的含C量,含C較高的Pt/C薄膜的XRD譜線低而寬,具有非晶態(tài)衍射特征。在500℃測(cè)量溫度下,以Pt/C薄膜為電極的YSZ氧氣濃差電池的電動(dòng)勢(shì)及電流輸出高于傳統(tǒng)的Pt電極。

Abstract:研究了微量Sc對(duì)Al-Cu-Li-Zr合金微觀組織和拉伸性能的影響。結(jié)果表明:添加0.1%Sc(質(zhì)量分?jǐn)?shù),下同)能消除鑄態(tài)合金的枝晶組織,細(xì)化合金的晶粒。合金鑄錠在隨后的均勻化和熱加工加熱過(guò)程中,析出細(xì)小、彌散的次生Al3Sc質(zhì)點(diǎn),這種質(zhì)點(diǎn)強(qiáng)烈地釘扎合金中的位錯(cuò)和亞晶界,從而有效地抑制合金的再結(jié)晶,具有亞結(jié)構(gòu)強(qiáng)化和直接析出強(qiáng)化作用。加入微量Sc后,Al-Cu-Li-Zr合金的強(qiáng)度大大提高,并且合金的塑性也得到明顯改善。

Abstract:The reactive Gibbs free energies, the reactive formation enthalpies and adiabatic temperatures concerning the preparation ofMoSi2-WSi2 composites using elemental powders of Mo, W and Si by the thermal explosion mode of SHS have been theoreticallycalculated and investigated by experiments. XRD, SEM and EDAX have analyzed the phase compositions and micro-area chemicalanalyses of the products. The results show that the reactive formation enthalpies of MoSi2 and WSi2 are biggest, 234.645 kJ/mol and195.670 kJ/mol respectively, when the reactions take place at 1685 K (the melting point of Si). And when the initial temperature is 1685 Kthe products of all systems have fused completely. Pure MoSi2-WSi2 composites are fabricated by the thermal explosion mode of SHS, andMoSi2-WSi2 exists as solid solution of (Mox,W1-x)Si2 while the chemical elements of every grain are not uniform.

Abstract:借助掃描電鏡(SEM)原位拉伸觀察了純鉬退火態(tài)纖維狀組織斷裂過(guò)程中裂紋萌生與擴(kuò)展的動(dòng)態(tài)變化過(guò)程,對(duì)其微觀斷裂特征進(jìn)行了研究。結(jié)果表明:加載初期,裂紋在與最大主應(yīng)力平面成45°的位置萌生,隨后逐漸張開(kāi)并鈍化;加載中期,新的裂紋在鈍化的主裂紋前方某處萌生。隨著載荷增加,裂紋呈“Z”字形相互連接;加載末期,裂紋失穩(wěn)擴(kuò)展,試樣斷裂。在裂尖應(yīng)力場(chǎng)作用下,裂紋擴(kuò)展遵循鈍化-萌生-鈍化的循環(huán)方式。純鉬試樣斷裂后,沿厚度方向有明顯的頸縮,斷口表面呈薄層狀纖維撕裂,并伴有剪切唇和韌窩的出現(xiàn),呈延性斷裂特征。

Abstract:根據(jù)改進(jìn)分析型嵌入原子模型(MAEAM),通過(guò)計(jì)算釩的總能量隨溫度的變化關(guān)系確定其熔點(diǎn)為2160±10K,與實(shí)驗(yàn)值(2175K)一致。運(yùn)用分子動(dòng)力學(xué)方法(MD)從原子面密度函數(shù)、面結(jié)構(gòu)因子、面徑向分布函數(shù)三個(gè)方面研究了V(111)晶面的預(yù)熔現(xiàn)象和熔化情況,發(fā)現(xiàn)V(111)面在800K左右開(kāi)始出現(xiàn)預(yù)熔。

Abstract:In order to investigate the microstructural evolution of Ni3Al intermetallic from Al and Ni powders during self-propagating high-temperature synthesis (SHS), a combustion front quenching method (CFQM) was used for extinguishing the propagating combustion wave. The microstructures on the quenched sample were observed with scanning electron microscope (SEM) and analyzed with energy dispersive spectrometry (EDS), the temperature of the combustion reaction was tested, and the phase constituent of the synthesized product was inspected by X-ray diffraction (XRD). The results show that the combustion reaction started with melting of the Al particles, and the melting results in partial dissolution of the Ni particles. With interdiffusing between Ni and Al atoms, reaction-diffusing layer of Ni3Al forms on the surface of the undissolving Ni particles and become thicker and thicker continually. Also, the reaction is incomplete, and this is because the coarser Ni and Al powders are used in the present work.

Abstract:The effects of Ni-P coatings on the electrochemical properties of La0.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy electrode was studied. The kinetic properties of the alloy electrode were evaluated. The results show that the cycling stability of the electrode is improved. The Ni-P coated powder electrode is better than bare electrode in exchange current density I0, Limiting current density I1, high rate dischargeability and hydrogen diffusion coefficient D. It is found that the surface microencapsulation is ineffective in prohibiting disintegration, main reason for which is probably ascribed to the larger expansion of the La0.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy hydride.

Abstract:用壓痕法測(cè)量EB-PVD熱障涂層的彈性模量及斷裂韌性。發(fā)現(xiàn)熱障涂層的Vickers顯微硬度和彈性模量隨施壓載荷增大而減小,當(dāng)載荷為2.94N時(shí),顯微硬度和彈性模量接近穩(wěn)態(tài)值,分別為6.3GPa和172GPa;斷裂韌性平均值約為1.81MPa·m1/2。壓痕法測(cè)得陶瓷層斷裂韌性數(shù)據(jù)波動(dòng)較大,其主要原因是陶瓷層顯微結(jié)構(gòu)不均勻,使壓痕裂紋在涂層不同局部區(qū)域所遇到的擴(kuò)展阻力不同。

Abstract:Five ternary complexes have been synthesized from europium with aromatic carboxylic acid(p-methylbenzoic acid, methoxybenzoic acid, m-chlorobenzoic acid, benzoic acid, p-hydroxylbenzoic acid) and acrylamide; and also characterized by means of elemental analysis, thermal analysis, FT-IR spectra and UV spectra. Fluorescence spectra show five ternary complexes have nice luminescent properties, the sequence of ability that the aromatic carboxylic acids transfer light energy to europium ion is as follows: benzoic acid > p-methylbenzoic acid > methoxybenzoic acid > m-chlorobenzoic acid > p-hydroxylbenzoic acid. At the same time, the ternary europium complexes containing a reactive ligand acrylamide will possibly have potential application on the fabrication of bonding-type europium polymer luminescent materials.

Abstract:In this work, 1,4-dioxane (cyclic ether ) was used to pre-treat the surface of Li electrode in order to passivate Li electrode and improve its interfacial stability and charge/discharge cycleability. It Is found that 1,4-dioxane can polymerize and form a good SEI passivating layer on the surface of Li electrode. This layer is able to enhance the interfacial stability of Li electrode without depress its kinetic behavior. Further measurements of charge/discharge efficiency of treated/bare Li electrodes and cycleability of Li metal cells fabricated with different Li anodes show that the Li electrode treated with 1,4-dioxane has higher charge/discharge efficiency compared with that of bare Li electrode, and the cell with such anode has better discharging performance and cycle life.

Abstract:Besides improvement of the magnetic refrigerant materials for development of magnetic refrigeration, an excellent magnetic field source is same important. Based on the hollow cylindrical flux source, a permanent magnetic circuit is designed for rotating room-temperature refrigerator. And after optimization by Ansys software, a permanent magnetic circuit, in which the average magnetic induction strength at the center of the working gap is up to 1.75 T, is got. Relative to the unoptimization magnetic circuit by Ansys software, the average magnetic induction strength in the center gap raise by 20%, and the magnetic circuit weight descend by 21%.

Abstract:ZrSiN film was selected as diffusion barrier and sputtered on polished titanium substrate with RF reactive magnetron sputtering. XRD, XPS and SEM results reveal that the ZrSiN diffusion barrier is a nano-composite that consists of nano-crystallite ZrN and amorphous-like SiNx phase. The results also show that in the surface of Ti substrate without ZrSiN diffusion barrier, there is Ti oxides, however, in the surface of Ti substrate with ZrSiN diffusion barrier, there is not Ti oxides and does only Zr, Si, N and O. This proves that ZrSiN diffusion barrier protect the Ti substrate against oxidation. The three-point bending test results prove that ZrSiN diffusion barrier significantly improves the bonding strength between Ti substrate and porcelain. The ZrSiN diffusion barrier with high Si content results in higher adhesion strength of the Ti/porcelain. This indicates that amorphous Si-N phase of ZrSiN diffusion barrier improves its barrier property.

Abstract:一氧化鈮(NbO)具有與金屬相近的導(dǎo)電能力,作為陽(yáng)極賦能時(shí),與鋁、鉭、鈮等閥金屬一樣,能在陽(yáng)極表面形成介電性能優(yōu)良的無(wú)定型氧化膜。研究了真空碳還原Nb2O5制備N(xiāo)bO的原理、工藝條件以及一氧化鈮粉末的理化性能和電性能等,參照GB/T3137-1995關(guān)于電容器用鉭粉電性能測(cè)試方法,經(jīng)實(shí)測(cè),一氧化鈮粉末具有比電容105120μF·V/g,損耗11.2%,漏電流2.5×10–4μA/μF·V,表明其濕式電性能已達(dá)到甚至優(yōu)于相應(yīng)的高比容鉭粉的水平;沿用鉭電容器生產(chǎn)工藝,探索性地進(jìn)行了小批量以NbO為陽(yáng)極的電解電容器生產(chǎn),其成品合格率達(dá)到77%。

Abstract:利用放電等離子燒結(jié)(SPS)技術(shù),原位制備了Ti2AlC/TiAl復(fù)合材料,研究了多步熱處理對(duì)Ti2AlC/TiAl顯微組織與力學(xué)性能的影響.結(jié)果表明,通過(guò)多步熱處理,Ti2AlC/TiAl的力學(xué)性能得到明顯改善.其中在1390℃熱處理時(shí),彎曲強(qiáng)度達(dá)到957.9 MPa,斷裂韌性達(dá)到20.73 MPa·m1/2.通過(guò)多步熱處理,可以得到雙態(tài)組織和晶粒更為細(xì)小均勻的近y組織的TiAl基體,復(fù)合材料的斷裂模式轉(zhuǎn)變?yōu)榇┚Ы饫頂嗔?在熱處理過(guò)程中,Ti2AlC能夠顯著抑制TiAl基體中y晶粒和α2/y層片晶團(tuán)的長(zhǎng)大,并且在一定程度上,阻礙α2/y層片晶團(tuán)的形成.

Abstract:Zr41.2Ti13.8Ni10Cu12.5Be22.5 bulk amorphous alloy was prepared by arc-melting and rapid casting into a copper mould. The rapid viscous flow of the bulk amorphous alloy was studied by the energy storage and the energy fast releasing. It is shown that the rapid viscous flow deformation, forming, welding can be carried out in the supercooled liquid region. And micro gear and same materials jointing is prepared successfully. There is no crystallization phase in the forming part and welding seam area. The tensile strength of the welded seam area is the same as that of the bulk amorphous matrix materials.

Abstract:在氫氣氛中機(jī)械球磨鑄態(tài)Nd12Fe82B6(at%)合金,利用機(jī)械力驅(qū)動(dòng)使之發(fā)生歧化反應(yīng),隨后進(jìn)行真空脫氫-再結(jié)合處理,獲得納米晶合金粉末材料.采用差示掃描量熱法(DSC),分析了歧化態(tài)合金粉末的脫氫-再結(jié)合行為.利用X射線衍射(XRD),掃描電鏡(SEM),及透射電鏡(TEM)等測(cè)試方法,研究了球磨及脫氫-再結(jié)合過(guò)程中合金粉末的相變與微觀組織.結(jié)果表明在0.2 MPa氫氣氛中球磨20 h,可使Nd12Fe82B6合金完全歧化,形成晶粒尺寸約為8 nm的Nd2H5,Fe2B和α-Fe的納米歧化組織,并且粉末顆粒細(xì)化到0.5μm～1.0 μm.在760℃,30 min的條件下進(jìn)行真空脫氫-再結(jié)合處理,獲得了平均晶粒尺寸約為30 nm的Nd2Fe14B/α-Fe納米復(fù)相Nd12Fe82B6合金粉末.

Abstract:The wetting behaviors of the Sn-8Zn-3Bi-(0~5)In alloys on Cu substrate were tested by an area-of-spread method. The spreading areas of these alloys increase with the addition of In before In content reaches 0.5wt%, which indicates small addition of In can improve the wettability of Sn-8Zn-3Bi based alloys. Bubble's largest pressure method was applied to measure the surface tensions of the Sn-8Zn-3Bi-(0~1.5)In melts. Adding 0.5wt% In into the foundry alloy, the surface tension of the alloy is lower than that of the other alloys. But more addition of In causes degradation of the surface tension. Wetting balance method was used to evaluate the wetting forces of these solders on Cu substrates. With addition of 0.5wt% In, wetting force reaches the maximum, which results from decrease of the solder/Cu interfacial tension.

Abstract:Raw powder of ZnFe2O4 and V-doped ZnFe2O4 were obtained by the citrate pyrolysis, and the effect of V doping on phase constituents, resistance-temperature behavior and gas-sensing properties to benzene and its derivatives were studied. The results demonstrate that as the increase of V doping amount, raw powder is the spinel structure, the resistance of ZnFe2O4 sensor decrease, and the sensitivity to benzene and its derivatives at higher operating temperature increase.

Abstract:According to the heat transfer analysis of Airslip mold, an analytical model was presented to study the solidification shell thickness and the critical solidification shell thickness. The theoretical analysis and experimental results indicate that the product of solidification shell thickness and the casting rate is a constant, when the casting rate increases, the solidification shell thickness decreases and the billet surface is better, the variation of the casting rate brings the fluctuation of solidification shell thickness and therefore deteriorates the billet surface. It is also shown that the product of billet diameter and the casting rate is a constant, too. When the billet diameter increases, the casting rate should be reduced correspondingly.

Abstract:The effects of additive species, additive concentration, temperature, anode to cathode distance and current density on the electrochemical synthesis of tantalum ethoxide using sacrificing anode method have been investigated. The optimum conditions were tetramethylammonium chloride 0.04 mol/L, boiling temperature, distance 2 cm and current density 220 A/m2. After treating the mixed solution with general distillation and reduced distillation, the final product were characterized by fourier transform infrared(FTIR) spectrum, Raman spectra and elemental analyses. The product is tantalum penta-ethoxide. Current efficiency is more than 95%, and recovery ratio of tantalum during distillation is 82.8%.

Abstract:Titanium diboride (TiB2) appears to be a promising material for corrosion prevention in aluminium industries. This paper first predicted the possibility of TiB2 formation in Ti-B-C system, and then focused on the preparation of TiB2 coatings by electroplating on the graphite in fluoride-chloride electrolytes (KF-KCl) containing K2TiF6 and KBF4 as the electrochemically-active components. The effect of current density and electroplating techniques on the surface leveling, compaction and grain size of coatings was investigated. The results show thick, adherent and uniform TiB2 coatings are obtained when the current density is 0.8 A/cm2; compared with continuous current plating (CCP), the surface leveling and compaction of coatings deposited by periodically interrupted current (PIC) are remarkably improved, and the crystal grain is finer. XRD analysis indicats that the coatings are composed of relatively pure TiB2 and the preferred orientation of coatings is (001) plane under experimental conditions, which is in accordance with the prediction of the two-dimensional crystal nuclei theory.

Abstract:The microhardness of JCW-S-AM coatings prepared by high velocity electric arc spraying on conditions of different process parameters was tested by hardometer. According to the test results, the model on the relation between the JCW-S-AM coatings microhardness and the process parameters was established by means of GA-BP genetic neural network arithmetic. The optimum parameters were optimized with genetic algorithm. The results of analysis and calculation show that the spray voltage and spray current all affect the microhardness, and there exists certain interaction between spray voltage and spray current. By means of genetic algorithm, the optimum spray parameters theoretically are that spray voltage is 29 V, spray current is 200 A, the microhardness of JCW-S-AM coatings is biggest.

Abstract:用人工神經(jīng)網(wǎng)絡(luò)預(yù)測(cè)了電鑄自支撐金剛石-鎳復(fù)合膜中金剛石顆粒的含量、復(fù)合膜的厚度和表面微觀形貌。結(jié)果表明,當(dāng)陰極電流密度小于1.0A/dm2時(shí),復(fù)合膜的表面均勻,無(wú)鎳瘤;復(fù)合膜的沉積速率約為14μm/h。其預(yù)測(cè)的沉積結(jié)果與實(shí)際樣品測(cè)量值接近,相對(duì)誤差小于9.9%。人工神經(jīng)網(wǎng)絡(luò)能夠充分體現(xiàn)電鍍工藝參數(shù)與沉積結(jié)果之間的非線性關(guān)系和隱含關(guān)系,訓(xùn)練精度較高,具有較高的預(yù)測(cè)能力。

Abstract:采用考慮熱機(jī)耦合效應(yīng)的剛塑性有限元方法,對(duì)正方體形7075鋁合金的鍛造過(guò)程和晶粒細(xì)化過(guò)程進(jìn)行了數(shù)值模擬,所采用的晶粒細(xì)化模型為Yada模型。結(jié)果表明,鍛件內(nèi)的應(yīng)力、應(yīng)變、應(yīng)變速率、溫度分布不均,模型中心區(qū)域?yàn)橐鬃冃螀^(qū),4個(gè)縱向棱邊區(qū)和以上下接觸表面為底面的接觸錐形區(qū)為難變形區(qū)。細(xì)化首先開(kāi)始于易變形區(qū),再相繼擴(kuò)展到縱向棱邊區(qū)和接觸錐形區(qū)。應(yīng)變速率和溫度是決定晶粒尺寸的主要因素。增加應(yīng)變速率,可使晶粒尺寸變小,但高應(yīng)變速率使得鍛件升溫;而溫度升高,使得晶粒尺寸長(zhǎng)大。有利于晶粒細(xì)化的鍛造工藝條件為:溫度350℃~400℃,應(yīng)變速率70s-1~100s-1,道次壓縮比20%~25%。討論了Yada模型的局限性,指明了它的適用范圍。

Abstract:The effect of the noble and heavy metal ion brighteners in acidic electroless nickel solution on properties of coatings including hardness, bonding force, porosity and corrosion resistance were investigated. These brighteners play a dominant role in coating structure from the measurements of AFM, XRD and XPS. The results show that the noble metal ion brighteners can greatly improve the electroless nickel coating performance, for example, reducing the surface coarseness and making the layer column smaller. Moreover, the amorphous structure get more remarkable due to presence of noble and heavy metal ion brighteners. XPS results reveal that Ni element exists in the form of Ni0 and Ni2+, while P exists in the form of negative ion and PO43-. So the brighteners are propitious to form protective film of Ni3(PO4)2.

Abstract:采用DTA分析Ti-23Al-25Nb合金和Ti-23Al-25Nb-0.36Y合金的相變特征,并根據(jù)DTA曲線特征制定熱處理工藝,用SEM,XRD分析熱處理后合金試樣的顯微組織及相組成,用TEM分析原始組織中釔的存在形式,用Instron-5569萬(wàn)能材料試驗(yàn)機(jī)進(jìn)行室溫壓縮試驗(yàn)。結(jié)果表明,釔在原始組織中以Y2O3形式存在;釔沒(méi)有改變Ti-23Al-25Nb合金的相變溫度;加入釔后,在1320℃淬火,B2相晶粒比較粗大,隨著淬火溫度的降低,O相增加,并且O相板條變細(xì)而雜亂,有利于提高合金的塑性和抗蠕變性能;加入釔后,合金強(qiáng)度提高,原因是第二相粒子Y2O3彌散強(qiáng)化的結(jié)果。

Abstract:通過(guò)交流電沉積的方法在鋁陽(yáng)極氧化膜的孔內(nèi)沉積金屬銅,制備了鋁基抗菌功能性材料;測(cè)試了沉積銅的鋁陽(yáng)極氧化膜的抗菌性能。結(jié)果表明:電沉積銅的鋁陽(yáng)極氧化膜對(duì)大腸桿菌、綠膿桿菌、糞鏈球菌和金黃色葡萄球菌的抗菌率均大于95%。透射電子顯微鏡表征了銅在氧化膜孔內(nèi)的沉積形貌,銅在鋁陽(yáng)極氧化膜孔內(nèi)呈連續(xù)的線狀形貌,直徑為25nm。

Abstract:采用化學(xué)共沉淀法制備納米級(jí)氧化銦錫復(fù)合粉體前驅(qū)物,煅燒得到納米級(jí)氧化銦錫(ITO)復(fù)合粉體,用TG-DTA,XRD,TEM,ICP-AES,XRF和BET研究了納米級(jí)ITO復(fù)合粉體的性能。前驅(qū)物銦錫氫氧化物的分解溫度為291.5℃,300℃下燒結(jié)即可得到立方結(jié)構(gòu)的ITO結(jié)晶粉體,Sn嵌入到In2O3晶格中,形成單相的ITO固溶體顆粒。隨著溫度的升高,ITO固溶體顆粒結(jié)晶更完全,晶粒長(zhǎng)大。前驅(qū)物銦錫氫氧化物分別在600℃,800℃和900℃煅燒4h得到粒度均勻、分散性好、粒徑為20nm~30nm的類(lèi)球形ITO復(fù)合粉體。600℃煅燒得到的ITO復(fù)合粉體的純度為99.995%,配比為In2O3:90.045%,SnO2:9.955%,比表面積為50.88m2/g。該粉體燒結(jié)活性高,將該粉體用簡(jiǎn)單的燒結(jié)工藝在1000℃燒制的ITO靶材相對(duì)理論密度達(dá)到99.25%。

Abstract:先驅(qū)體聚鋁碳硅烷經(jīng)熔融紡絲、空氣預(yù)氧化處理、1300℃燒成制得連續(xù)的含有少量鋁和較多氧的SiC(OAl)纖維,即KD-A纖維。通過(guò)元素分析、拉伸強(qiáng)度測(cè)試及SEM,AFM,HRTEM,XRD等分析對(duì)纖維進(jìn)行了表征。結(jié)果表明:連續(xù)KD-A纖維是非晶型的含鋁SiC纖維,直徑為12μm~14μm,具有較高的抗拉伸強(qiáng)度(2.6GPa)和彈性模量(210GPa),其耐高溫和抗氧化性能明顯優(yōu)于Nicalon纖維,達(dá)到了Hi-Nicalon纖維的水平。

Abstract:The particle reinforced aluminum alloy matrix composites, (Al2O3+Al3Zr)p/A359, was fabricated by In-situ reaction in melt A359 and Zr(CO3)2 system. During the fabrication process, a low frequency alternative electromagnetic field was employed to improve the properties of composites by EMS (electromagnetic stirring). The results of dry sliding friction experiments indicate that the wear resistance of composites is better than that of pure matrix alloy. And the wear resistance of composites under a heavy load is further improved by imposing EMS in the fabrication process. By comparison with the composites fabricated without imposing EMS, the critical transition load from mild wear to severe wear of the composites increases from 58.8 N to 78.8 N. The scanning electron microscopy (SEM) analysis of worn-out surfaces indicate that the wear mechanism of pure matrix alloy is adhesive wear and spalling wear, that of composites without EMS in fabrication is mainly abrasion and that of electromagnetic fabricated composites is pure abrasion.