Characterization of Ti-Cu Films Deposited by HPPMS and Effect on NO Catalytic Release and Platelet Adhesion Behavior

Ti-Cu films with different Cu concentrations were fabricated by high-power pulsed magnetron sputtering(HPPMS) to release copper ions and catalyze NO to improve the blood compatibility. The Cu concentrations of films were 25.7 at% and 68.8 at%. Pure Ti films were also fabricated. Copper release, catalytic release of nitric oxide(NO), and blood platelet adhesion of Ti-Cu films were studied. Ti-Cu films released copper ions in PBS solution and more Cu ions were released from films with 68.8 at% Cu. Ti-Cu films had excellent ability of catalytical decomposition of exogenous donor S-nitroso-N-acetyl-DL-penicillamine(SNAP) and as a result, nitric oxide(NO) was generated. The NO generation catalyzed by Ti-Cu films was significantly higher than that by pure Ti films. This was more eminent in the Ti-Cu films with 68.8 at% Cu. The platelet adhesion and activation of Ti-Cu films were significantly inhibited compared to that of pure Ti films in the presence of SNAP. The Ti-Cu film fabricated by HPPMS showed the ability of releasing Cu ions to catalyze SNAP to generate NO to inhibit platelet adhesion and activation.     

The Process of TiB2-Cu Composite Phase and Structure Formation during Combustion Synthesis

The reaction process of combustion synthesis for TiB2 -Cu was investigated in detail using combustion-wave arresting experiment, X-ray diffraction （ XRD ） analysis, SEM analysis and differential thermal analysis （ DTA ）. The XRD analysis results for the different parts of the quenched specimen show that TiCux intermetallic phase firstly forms with the propagation of combustion wave, and then Ti1.87 B50 and Ti3B4 metastable phases come forth due to the diffusion of B atoms and finally the stable TiB2 phase forms because of the continuous diffusion of B atoms. The formation of TiB2 phase is uot completed by one step, but undergoes several transient processes. The process of reaction synthesis for Ti-B-Cu ternary system can be divided into three main stages： melting of Cu and Ti , and the formation of Cu- Ti melt and few TiCux , TiBx intermetallic phases ; large numbers of TiCux intermetallic phases formation and some fine TiB2 particles precipitation ; and the TiB2 particles coarsening and the stable TiB2 and Cu two phases formation in the final product.     

Microstructural evolution during self-propagating high-temperature synthesis of Ti-Al system

In order to investigate the microstructural evolution during self-propagating high-temperature synthesis （SHS） of Ti-Al powder mixture with an atomic ratio of Ti： Al=1：1, a combustion front quenching method （CFQM） was used for extinguishing the propagating combustion wave, and the microstructures on the quenched sample were observed with scanning electron microscope （SEM） and analyzed with energy dispersive spectrometry （EDS）. In addition, the combustion temperature of the reaction was measured, and the phase constituent of the synthesized product was inspected by X-ray diffraction （XRD）. The results showed that the combustion reaction started from melting of the Al particles, and the melting resulted in dissolving of the Ti particles and forming of Al3Ti grains. As the Al liquid was depleted, the combustion reaction proceeded through solid-state diffusion between the solid Al3Ti and the solid Ti. This led to the forming of TiAl and Ti3Al diffusing layers. In addition, the combustion reaction is incomplete besides TiAl, there are a large amount of Ti3Al and TiAl3 and a small amount of Ti in the final product. This incompleteness chiefly results from the using of coarser Ti powder.     

Thermodynamic Analysis of the Formation of In-situ Reinforced Phases In Cast AI-4.5Cu Alloy

The thermodynamic analysis of the formation of in-situ reinforced phases in (TiB2 Al3Ti)/Al-4.5Cu composites prepared by mixed salts reaction was conducted, and heat changes of mixed salts system were analyzed by differential thermal analysis (DTA). The results show that although TiB2 possesses the strongest formation ability in Al-Ti-B ternary system, [Ti] is relatively excessive in the in-situ reaction and it combines with Al to form Al3Ti phase. The reinforced phases are TiB2 and Al3Ti in the produced composites due to the reaction taking place to form reinforced phase with the addition of mixed salts into Al-4.5Cu melt between 900℃ and 1032℃.     

Kinetics of Combustion Synthesis in Ti-C-3Ni-Al System

The Kinetics and mechanisms of the combustion reaction in theTi-C-3Ni-Al system were studied. Samples were prepared by igniting compacts of elemental Ti, C, Ni and Al powders with a heating tungsten coil under an inert argon atmosphere. The activation energies of Ti+C+50wt%(3Ni+Al)→TiC+50%Ni3Al and Ti+C+80wt%(3Ni+Al) →TiC+80%Ni3Al exothermic reactions were determined by measuring the combustion wave velocity and the combustion temperature, which are 129kJ.mol-1 and 79kJ*mol-1, respectively. The mechanism of formation of products for Ti-C-3Ni-Al system was found:metal phases (Ti-3Ni-Al) are melted in combustion process,and carbon dissolves into the liquid metal and TiC is subsequently precipitated out of solution, and Ni3Al is crystallized during the cooling process. The mechanism is fairly similar with that of Ti+C→TiC and Ti+C+Ni→TiC+Ni. There are two reactions (Ti+C→TiC, 3Ni+Al→Ni3Al) in the Ti+C+3Ni+Al system, and the wave velocity is mainly controlled by the velocity of Ti + C→TiC, but the velosity of 3Ni+Al→Ni3Al may play a significant role when Ni3Al contents are higher than 70wt%.     

Cl~- induced synthesis of submicron cubic copper particles in solution

Submicron copper microcrystal was synthesized by reducing Cu2O with hydrazine hydrate as reducer in aqueous solution,and was characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The shapes of copper microcrystal depend on additives. Cubic copper particles were observed when the inorganic salt containing Cl^-,such as NH4Cl,NaCl,or KCl,was added into the reaction system. By combined use of NH4Cl and polyvinylpyrrolidone （PVP）,the proportion of cubic copper particle number exceeded 90%,and the particle size is 0.1-0.5μrn. While other inorganic salt without Cl^-,such as Na2SO4 or （NH4）2SO4,had little effect on the shapes of the copper particles. The growth mechanism of metallic copper crystal in aqueous solution was analyzed. It is suggested that the formation of cubic copper crystals is ascribed to the selective adsorption of Cl^-on copper crystal （100） faces.     

Mechanism of combustion synthesis of TiC-Ti cermet

In order to investigate the mechanism of combustion synthesis of TiC-Ti cermet, a mixture of Ti and C was used for a combustion front quenching test, and the microstructural evolution in the quenched sample was analyzed by scanning electron microscopy （SEM） and energy dispersive X-ray （EDX）. Also, a temperature-time profile of the combustion reaction was measured. Based on the experimental results, a reaction-dissolution-precipitation mechanism of the combustion synthesis of TiC-Ti was proposed.     

Preparation of porous silicon carbide by combustion synthesis

Porous silicon carbide ceramics were prepared by combustion synthesis technique. SiC/TiC composite was gained by combustion reaction of Si, C and Ti. Thermodynamics analysis of Si-C-Ti system indicates that the content of TiC in products should be larger than 30%. The experimental results show that the content of Ti C should be larger than 25% to achieve a complete combustion reaction. The X-ray diffractometry results show that the final products with a relative density of 45%-64% are composed of a-SiC,β-SiC, TiC and a small quantity of Si. The images of scanning electron microscopy show that the structures of grain in SiC based porous ceramics consist of particles with a few microns in size.     

Novel titanium particles reinforced Zr-based bulk metallic glass composites prepared by infiltration casting

A novel Ti /Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 composite was successfully prepared by infiltrating the melt into sintered Ti preform. It shows that the introduction of Ti particles into the composite results in an increase in elastic strain to 3% and an enhancement of the strength up to 2.1 GPa. High specific strength has been obtained because of the decrease in density of the composite. It is suggested that an improvement in the mechanical properties of the composite may be attributed to the generation of multiple shear bands and some deformation in the Ti particles.     

片状钛酸钡颗粒的熔盐法制备及其形貌

为了得到有利于晶粒择优取向的片状钛酸钡形貌颗粒,采用合成出的片状模板原料,通过熔盐法制备了片状钛酸钡颗粒.首先,以碳酸钾、二氧化钛和钛酸锂为原料,在氯化钾熔盐中制备了具有类纤铁矿层状结构的钛酸盐（K0.8Ti1.73Li0.27O4）.经酸交换后,得到了片状钛酸（H1.07Ti1.73O4,HTO）颗粒.HTO是一种具有层间通道结构和良好的离子交换性的片状模板,以HTO和碳酸钡为原料,氯化钠和氯化钾为熔盐,在820℃保温5h得到纯相的钛酸钡,其颗粒形貌呈现为宽5～8μm、长10～15μm,厚度约1μm左右的片状形貌,而且这些片状颗粒是由1μm的小片状颗粒按特定晶向排列而成.结果表明以HTO为模板的原位反应机制起了主要作用,产生保持了片状HTO模板形状的片状钛酸钡颗粒.该方法有望为制备织构化陶瓷提供良好各向异性钛酸钡粉体.     

The Combustion Synthesis Process of Al-Ti-C System in an Elevated-temperature Al-melt

One of the main disadvantages of combustion synthesis of ceramic/metal composite materials is the relatively high level of porosity present in the products. To synthesize TiC/ Al composites with a dense structure, this paper proposes a novel application of an elevated-temperature Al-melt to directly ignite and simultaneously in-filtrate Al-Ti-C preform dipped in the melt. The emphasis was placed on the combustion synthesis process and mi-crostructural evolution of the preform in the melt, by a liquid quenching test combined with the measurtment of the temperatwe history of the dipped preform. The results show that the combustion synthesis process of the preform in the elevated-temperature melt involves a series of reactions, and that higher temperature of the melt is favourable for the formation of TiC. The synthesized TiC / Al composites exhibit a dense strucame, which is attributed to the infiltration of the melt into the preform.     

Synthesis of Ti3SiC2/TiB2 Composite by In-situ Hot Pressing (HP) Method

Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power mixtures.Volume fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions process.TiC and Ti5Si3 were two important intermediate phases during the whole reactions.The microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix.     

Thermodynamic analysis of the formation of <Emphasis Type="Italic">In-situ</Emphasis> reinforced phases in cast Al-4.5Cu alloy

The thermodynamic analysis of the formation of in-situ reinforced phases in （TiB2＋Al3Ti）/Al-4.5Cu composites prepared by mixed salts reaction was conducted, and heat changes of mixed salts system were analyzed by differential thermal analysis（DTA）.The results show that although TiB2 possesses the strongest formation ability in Al-Ti-B ternary system, [Ti] is relatively excessive in the in-situ reaction and it combines with Al to form AlaTi phase. The reinforced phases are TiB2 and AlaTi in the produced composites due to the reaction taking place to form reinforced phase with the addition of mixed salts into Al-4.5Cu melt between 900 ℃ and 1 032 ℃.     

制备方法对Ti50.2Ni29.8Cu20合金显微组织和相变行为的影响

采用常规铸造和快速凝固两种合金制备方法,分别制备出化学成分为Ti50.2Ni29.8Cu20的合金体材料和合金薄带,利用XRD(X射线衍射仪)、TEM(透射电子显微镜)、DSC(差示扫描量热仪)等手段研究这两种制备方法对Ti50.2Ni29.8Cu20合金的马氏体相变行为和显微组织方面的影响。实验结果表明,经500℃退火1h处理后,Ti50.2Ni29.8Cu20合金薄带中出现大量B19马氏体和少量Ti2Ni析出相,而固溶后的Ti50.2Ni29.8Cu20合金体材料只存在B19马氏体,同时相比于体材料,薄带的B19马氏体衍射峰强度减小及B19晶格常数a、b增大,而c减小;Ti50.2Ni29.8Cu20合金薄带的马氏体相变温度Ms比体材料的马氏体相变温度Ms低,且薄带的热滞△T也比体材料小。     

Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

The performance of Al-Ti-C master alloy in refining Al-10Mg and Al-5Cu alloys was studied by using electron probe micro-analyzer （EPMA） and X-ray diffractometer （XRD） analysis. The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds. Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading. However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti（Al, Cu）2, which is responsible for the refinement fading in Al-5Cu alloy. These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.     

Preparation of TiAl/Al_2O_3 composites by combustion synthesis

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Reaction dynamics in the combustion synthesis system of Al-CrO3-Al2O3-NaF-N2-O2

A new material with heat-resistant and adiabatic characteristics and high strength was prepared using the combustion synthesis method by mixed powders of CrO3, Al, Al2O3, and NaF in atmospheric gas. The reaction dynamic process of the Al-CrO3-NaF-Al2O3-N2-O2 new material system by the combustion synthesis method was discussed based on the observation results by SEM, EDS, and XRD in combination with the combustion front quenching method （CFQM） and the relation curves between reaction free enthalpies and the corresponding temperatures. The combustion synthesis mechanism and the formation reasons of the phase in the combustion product were analyzed.     

退火工艺对Ti50.2Ni29.8Cu20合金薄带中马氏体相变的影响

通过快速凝固法制备Ti50.2Ni29.8Cu20合金薄带,并利用XRD(X射线衍射仪)、DSC(差示扫描量热仪)、TEM(透射电子显微镜)等手段研究退火温度和退火时间对Ti50.2Ni29.8Cu20合金薄带马氏体相变的影响.结果表明,退火处理后Ti50.2Ni29.8Cu20合金薄带的室温相主要是B19马氏体和少量...     

Electroless plating composite coatings of Ni-Ti-Re on the surface of diamond

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Wetting behavior of graphite and CFC composites by Cu-Ti compacts

The wetting behavior of Cu-Ti powder compacts with 22 wt %Ti and 50 wt %Ti on carbon materials, including graphite and carbon fiber reinforced carbon composites(CFC), has been investigated in a vacuum using the sessile drop method. The equilibrium contact angles of Cu-22Ti(containing 22 wt%Ti) on the graphite and the CFC substrates at 1 253 K are 32 o and 26 o, respectively, whereas the equilibrium contact angle of 9° is obtained for Cu-50Ti(containing 50 wt%Ti) on both the graphite and the CFC substrates at 1 303 K.Microstructural analysis of the wetting samples shows that a thin TiC reaction layer is developed at the interfacial area and Ti-Cu intermetallic compounds are formed over the reaction layer. The investigation on the spreading kinetics of Cu-Ti compacts on carbon materials substrates at fixed temperatures reveals that the spreading is controlled by the interfacial reactions in the first stage and then by the diffusion of the active Ti from the drop bulk to the triple line in the later stage. The spreading is promoted by the intense reaction at higher Ti concentrations.