Effect of nano TiN/Ti refiner on as-cast and hot-working microstructure of commercial purity aluminum

A novel type nano TiN/Ti composite grain refiner （TiN/Ti refiner） was prepared by high energy ball milling, and its effect on as-cast and hot-working microstructure of commercial purity aluminum （pure Al） was investigated. The results show that TiN/Ti refiner exhibits excellent grain refining performances on pure Al. With an addition of 0.2% TiN/Ti refiner, the average grain size of pure Al decreases to 82 μm, which is smaller than that of pure Ti and Al 5Ti 1B master alloy as refiners. The microstructure of weld joint of pure Al with 0.1% TiN/Ti refiner is fine equiaxed grains and the hardness of weld joint is higher than that of the base metal. For pure Al with 40% cold deformation and recrystallization at 250 °C for 1.0 h, the grains of the sample added 0.1% Ti powder have an obvious grain growth behavior. In contrast, oriented grains caused by deformation have been eliminated, and there is no obvious grain growth in pure Al refined with 0.1% TiN/Ti refiner, indicating that nano TiN in the refiner inhibits the growth of grain during recrystallization.

Effects of nano TiN addition on the microstructure and mechanical properties of TiC based steel bonded carbides

TiC based steel bonded carbides with the addition of nano TiN were prepared by vacuum sintering techniques.The microstructure was investigated using scanning electron microscopy（SEM） and transmission electron microscopy（TEM）,and the mechanical properties,such as bending strength,impact toughness,hardness,and density,were measured.The results indicate that the grain size becomes small and there is uniformity in the steel bonded carbide with nano addition;several smaller carbide particles are also found to be inlaid in the rim of the larger carbide grains and prevent the coalescence of TiC grains.The smaller and larger carbide grains joint firmly,and then the reduction of the average size of the grains leads to the increase in the mechanical properties of the steel bonded carbides with nano addition.But the mechanical properties do not increase monotonously with an increase in nano addition.When the nano TiN addition accounts for 6-8 wt.% of the amount of steel bonded carbides,the mechanical properties reach the maximum values and then decrease with further increase in nano TiN addition.

Microstructure and Properties of Gradient Cemented Carbide with Nano-TiN

Gradient cemented carbides with nano-TiN were prepared by the common powder metallurgical procedure. The formation of gradient zone and the microstructure, properties of the alloys were investigated using scanning electron microscope（SEM）, energy dispersive spectroscopy（EDS） and other performance testing apparatus. Moreover, the effect of nano-TiN on the gradient cemented carbide was studied. It is found that gradient zone width increases slightly with nano-TiN introduction. Both cobalt and titanium concentrations reach the maximum near the gradient border. Tungsten concentration shows fluctuation from the surface to the bulk. （Ti ,W）C phase grains are refined for nitrogen introduction. Core-rim structure has been observed under the SEM back-scattered mode. The core appears as dark due to more titanium in it and the rim with more tungsten appears as grey. In addition, the hardness and transverse rupture strength of gradient cemented carbide are enhanced with nano-TiN introduced.

Preparation of tin-oxide nanotubes as anode for Li-ion batteries

The influence of nanostructure on the electrochemical properties of Li-ion battery was investigated. Tin-oxide nanotubes were prepared by combining sol-gel method with polycarbonate template. Scanning electron microscopy and X-ray diffractometry were applied to characterize the obtained material. The electrochemical measurements were conducted on the nanostructured tin-oxides as electrode of Li-ion batteries. The XRD data indicate that the wall of tube is composed of cassiterite crystals of several nanometers. The electrochemical measurements show that the reaction under potential 0.1-0.2 V is possibly related to the tubular structure of the material. It is suggested that the trapping of Li by dangling bonds and defects sites also contributes to the larger irreversible capacity loss in the first discharge.

A New-type of Cermets Cutter with Nano-TiN Addition:Microstructure, Mechanical and Cutting Properties

The microstructure and mechanical properties of a new-type of cermets cutter （ tool A ） with nano- TiN modification and its cutting properties in cutting gray cast iron are investigated. SEM and TEM observatioas of the microstructure of the above material reveal that nano- TiN modified cermets possess a finer microstructare than conventional cermets. In the cutting tests, for comparison, cemented carbide cutter （ YG8, tool B） was also utilized. The cutting results show that the cutting properties of tool A are superior to those of tool B. It is also Jound that the predominant failare mode of tool A is normal wear and micro-spalling under lower cutting quantities, and that chipping occurs under higher cutting quanthies . SEM analysis reveals that cohesion, oxidation and diffusion wear become very apparent at a higher cutting speed. On the contrary, grain wear also exists but is not apparent.

Activation and self-repairing effectiveness of lubrication with nano-tin as additives

Micron grade Sn powder, VG32 oil and active pharmaceutical were mixed and the Nanometer Sn lubricant additives were prepared. Nanometer additives with different Sn concentrations were used in Steel-brass Tribo-pair for friction and wear test. The activating method to nano-Sn and surface of brass samples was investigated, and the method to form relatively thick friction coating on samples was discussed. Surface elemental distribution, coating thickness and its surface appearance were analyzed with X-ray photoelectron spectrum （XPS）, auger electron spectrum （AES） and scanning electron microscope （SEM） respectively. The result shows that the ultra-thick friction coating （approx 20 μm）, with abundant tin and well combined with substrate, has formed on the brass sample. The friction coating revealed superior performance of friction reducing and antiwear properties. Therefore, the results possess practical significance to self-repair usage on steel-brass tribo-pair in mechanical systems.

Effect of Sn^(4+) content on properties of indium tin oxide nanopowders

Indium tin oxide(ITO)nanopowders were prepared by a modified chemical co-precipitation process.The influence of different SnO2 contents on the decomposition behavior of ITO precursors,and on the phase and morphology of ITO precursors and ITO nanopowders were studied by X-ray diffractometry,transmission electron microscopy and differential thermal and thermogravimetry analysis methods.The TG-DSC curves show that the decomposition process of precursor precipitation is completed when the temperature is close to 600 ℃and the end temperature of decompositionis somewhat lower when the doping amount of SnO2 is increased.The XRD patterns indicate that the solubility limit of Sn4+ relates directly to the calcining temperature. When being calcined at 700℃,a single phase ITO powder with 15%SnO2(mass fraction)can be obtained.But,when the calcining temperature is higher than 800℃,the phase of SnO2 will appear in ITO nanopowders which contain more than 10%SnO2.The particle size of the ITO nanopowders is 15-25 nm.The ITO nanoparticles without Sn have a spherical shape,but their morphology moves towards an irregular shape when being doped with Sn4+.

TiN-Al_2O_3纳米复合材料的力学性能和导电性能

以纳米TiN和α-Al2O3粉体为原料,采用球磨混合法制备了纳米TiN-Al2O3复合粉体,通过热压烧结得到致密烧结体.研究了纳米TiN颗粒对Al2O3材料力学性能和导电性能的影响,实验结果表明:在Al2O3基体中加入15vol％TiN纳米颗粒时,Al2O3材料的弯曲强度和断裂韧性分别从370MPa和3.4MPa·m1/2提高到690MPa和5.1MPa·m1/2,随着TiN添加量的增加,复合材料的电阻率逐渐降低,在25vol％TiN时达到最低值(6.5×10-3Ω·cm).

激光重熔参数对镍基纳米TiN复合电沉积镀层性能的影响

目的在Ni Cr20Ti Al基体材料上进行镍基纳米Ti N电沉积复合镀后再开展激光重熔工艺,研究激光重熔参数对镀层表面质量、结合力及硬度的影响。方法采用正交实验,研究不同激光重熔参数(扫描速率、搭接量、离焦量等)对重熔镀层的影响,采用显微硬度计、扫描电镜和划痕仪进行硬度、表面形貌和结合力检测,以得到较优工艺参数。结果通过控制重熔参数对镀层表面能量和表面形貌的影响,以降低表面性能差异,以得到了激光重熔较佳工艺参数为:电流115 A,脉宽为8 ms,频率为10 Hz,离焦量15 mm,扫描速度230 mm/min,使获得的镀层表面形貌比较平整,结合力提高到大于60 N,硬度值平均为632HV,并且硬度分布均匀。结论激光重熔工艺可消除纳米复合电沉积过程中产生的间隙,纳米复合镀层致密均匀,镀层与基体之间产生良好的冶金结合,镀层表面硬度分布均匀,力学性能趋近一致。

纳米TiN烟幕干扰激光和红外性能研究

在容积为20 m3的烟幕箱中,测试了30 g纳米TiN形成的烟幕对1.06μm激光、10.6μm激光、3~5μm红外及8~12μm红外的干扰性能,结果表明,纳米TiN烟幕对各波段红外辐射的遮蔽/干扰效果良好,质量消光系数均基本大于1 m2.g-1,与常规材料的烟幕性能比较表明,纳米TiN烟幕消光性能好,是一种能有效干扰1.06μm,10.6μm激光测试系统及3~5μm,8~12μm红外热像仪的新型烟幕材料。

纳米TiN粒子在Ni-TiN复合镀层中的作用研究

通过对超声-电沉积Ni-TiN复合镀层的研究,探讨了纳米TiN粒子对Ni-TiN复合镀层的表面形貌、成分、硬度、耐磨性能以及耐腐蚀性能的影响。结果表明,含有纳米TiN粒子的Ni-TiN复合镀层,不仅具有细密的显微结构,而且表现出优良的性能,如较高的硬度以及良好的耐磨性能和耐腐蚀性能。Ni-TiN复合镀层的磨损量大约为纯镍镀层的1/5,其平均腐蚀速率为纯镍镀层的1/3左右,20钢的1/5。

纳米TiN增强高铬铸铁铸渗层耐磨性的研究

采用CO2水玻璃砂型铸渗工艺在中碳铸钢ZG270-500表面制备了纳米TiN高铬白口铸铁铸渗层,研究了纳米TiN加入量对铸渗层组织显微硬度和耐磨性的影响。结果表明,在试验条件下,纳米TiN能够提高铸渗层的硬度,当加入量为1.0%时铸渗层具有最好的耐磨性能,加入量过多时纳米TiN有向界面处富集的趋势。

纳米TiN改性TiC基金属陶瓷刀具切削性能的研究

制备了纳米TiN改性的TiC基金属陶瓷刀片 ,并用该刀片与普通TiC基金属陶瓷刀片进行了对比切削试验。结果表明 ,添加TiN纳米粒子可有效改善TiC基金属陶瓷刀具的机械性能和切削性能 ,改性金属陶瓷刀片可以较高切削速度加工碳钢和合金钢 。

不同方式电沉积纳米TiN/Ni复合镀层的组织和耐磨损性能

采用直流电沉积、脉冲电沉积和超声-脉冲电沉积三种方式在45钢表面制备了纳米TiN/Ni复合镀层,分析了复合镀层的组织、显微硬度以及镀层中TiN的含量,并对复合镀层的耐磨损性能进行了研究。结果表明:直流电沉积复合镀层的晶粒最粗大,超声-脉冲电沉积复合镀层的晶粒尺寸最细小;直流电沉积复合镀层、脉冲电沉积复合镀层和超声-脉冲电沉积复合镀层的显微硬度以及镀层中TiN的含量依次增大;超声-脉冲电沉积复合镀层具有最佳的耐磨损性能,其磨损量为直流电沉积复合镀层的46%,显微硬度为604.72HV,镀层中TiN的质量分数为2.27%。

SiC/纳米TiN水基复合料浆特性及喷雾干燥

以四甲基氢氧化铵(TMAH)为分散剂,纳米TiN、亚微米SiC粉体为原料,分别制备单组分水基料浆及复合料浆,分析了SiC/纳米TiN复合料浆的分散稳定机制以及喷雾干燥行为.研究结果表明,TMAH在纳米TiN、SiC颗粒表面形成特征吸附,通过静电作用和空间位阻协同作用提高颗粒的分散性;当pH=8、TMAH加入量为0.75wt%时,复合浆料分散稳定,喷雾干燥制备的SiC/纳米TiN复合粉体流动性好,且分布均匀.

Ni-P-TiN(纳米)化学复合镀层研究

为了提高AZ31镁合金的耐磨性能并扩大其在相关领域的应用,采用化学复合镀技术在AZ31镁合金基体上制备了Ni-P-TiN(纳米)复合镀层,同时制备Ni-P镀层进行比较。研究了复合镀层形貌、成分、硬度和耐磨性能与镀液中纳米TiN颗粒含量的关系。结果表明,复合镀层和Ni-P镀层表面都是由胞状物排列而成;纳米TiN颗粒沉积于Ni-P-TiN(纳米)复合镀层中。当镀液中纳米TiN颗粒浓度为3g/L时,复合镀层硬度达最大值,为826HV,而Ni-P镀层只有508HV;同时复合镀层表现出优异的耐磨性能,在同等条件下其磨损失重只有Ni-P化学镀层的25%。

纳米结构TiN薄膜的制备与性能研究

利用自行研制的磁过滤等离子体设备 ,在室温条件下的不锈钢基底上成功地制备了性能良好的纳米结构TiN薄膜。运用原子力显微镜和X射线衍射仪对其结构和形貌进行了表征。利用纳米硬度仪测量了TiN薄膜的硬度和弹性模量。结果显示 :沉积的TiN薄膜表面非常平整光滑 ,致密而无缺陷 ;硬度远高于粗晶TiN的硬度 ;TiN晶粒尺寸在 3 0～ 5 0nm ;

TC4钛合金表面电弧离子镀TiN／CrN纳米多层薄膜研究

用电弧离子镀技术在TCA钛合金基体上通过改变偏压制备了4组TiN／CrN薄膜，对薄膜的表面形貌、厚度、相结构、硬度、膜基结合力和摩擦系数等组织、性能进行了测试表征。结果表明，薄膜是由TiN相和CrN交替叠加构成的纳米多层薄膜，薄膜的调制周期为60nm，总的厚度约为480nm。与基体钛合金相比，镀膜后样品的表面性能与偏压幅值密切相关并有显著提高：显微硬度从基体的3GPa提高到16．5-24．7GPa；摩擦系数从基体的0．35大幅度降低到0．14—0．17；薄膜与基体结合牢固，膜基临界载荷在60-80N之间。经电弧离子镀TiN／CrN纳米多层薄膜处理后，TC4钛合金可以满足沙粒和尘埃磨损条件下的耐磨性能要求。

纳米TiN提高金属陶瓷刀具耐磨损性能的机理研究

研究纳米TiN显著提高TiC基金属陶瓷刀具耐磨损性能的机理。结果表明 ,纳米TiN在晶界上的分布阻碍了TiC晶粒的长大 ,细化了金属陶瓷组织 ,提高了强度、硬度等力学性能 ,使金属陶瓷刀具的耐磨损性能提高。

脉冲偏压对电弧离子镀Ti/TiN纳米多层薄膜显微硬度的影响

采用脉冲偏压电弧离子镀方法在高速钢基体上沉积Ti/TiN纳米多层薄膜,采用正交实验法设计脉冲偏压电参数,考察脉冲偏压对Ti/TiN纳米多层薄膜显微硬度的影响.结果表明,在所有偏压参数(脉冲偏压幅值、占空比和频率)和几何参数(调制周期和周期比)中,脉冲偏压幅值是影响显微硬度的最主要因素;当沉积工艺中脉冲偏压幅值为900V、占空比为50%及频率为30kHz时,薄膜硬度可高达34.1GPa,此时多层膜调制周期为84nm,TiN和Ti单元层厚度分别为71和13nm;由于薄膜中的单层厚度较厚,纳米尺寸的强化效应并未充分体现于薄膜硬度的贡献中,硬度的提高主要与脉冲偏压工艺,尤其是脉冲偏压幅值对薄膜组织的改善有关.