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1.
采用单铜辊甩带法制备了Fe(84.5-x)SixB14.5.Cu1(x=0,2,2.5,3,4)非晶合金带材,并用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、振动样品磁强计(VSM)研究了Fe(84.5-x)SixB14.5Cu1合金带材的非晶形成能力、热稳定性和软磁性能。结果表明:Si元素能明显提高该体系合金的非晶形成能力,并提高了淬火态非晶合金带材的一级和二级起始晶化温度;通过合金的退火处理,合金带材析出的α—Fe纳米晶晶粒尺寸约为30nm;其中Fe(84.5-x)SixB14.5Cu1非晶合金带材经过460℃保温5min热处理后可以获得较高的饱和磁感应强度为1.82T.  相似文献   

2.
为了研究超声脉冲波在钢、铁、铝等金属棒内的传播规律。检验已有的声学理论,采用和金属声速接近的光学玻璃为样品,当超声垂直于样品侧壁入射时,利用研制的动态光弹成像系统研究了玻璃园棒内超声脉冲纵波、横波、瑞利波声场的传播特性。自动记录了0—99.9μs时间内各种超声波声场在玻璃园棒横截面上的传播图像(时间间隔0.1μs),由此来模拟超声脉冲波在金属棒横截面中的传播行为。  相似文献   

3.
机械合金化制备Nd60 Fe20 Al10 Co10非晶粉末的研究   总被引:1,自引:0,他引:1  
鲁小川  徐晖  阳松平  董远达 《功能材料》2003,34(6):647-648,651
利用机械合金化制备Nd60Fe20Al10Co10非晶粉末,采用X射线衍射(XRD)和振动样品磁强计(VSM)研究Nd60Fe20Al10Co10非晶的形成过程、磁性能变化及其与成分结构的关系。结果表明,90min后Al原子溶入Nd原子形成固溶体。球磨2h后出现少量非晶,20h后Co单质和Nd单质消失.组织为非晶相(含少量的α-Fe)。球磨100h最终得到非晶 少量的α-Fe纳米晶。球磨过程中,矫顽力随着合金中非晶的量增加而升高.球磨20h矫顽力达到43kA/m。Nd60Fe20Al10Co10合金具有硬磁性是由于非晶相的存在而造成的。  相似文献   

4.
FeCuNbSiB超微晶合金中晶化相-α-Fe(Si)固溶体(α相)的体积份数,尺寸和成分(Si含量)与合金中Nb含量有关。Nb含量的增加使FeCuNbSiB非晶合金在最佳温度退火后α相的体积份数减少,尺寸减小及Si含量降低。α相的体积份数,尺寸及成分(Si含量)对合金的起始磁导率有综合影响。对于合金获得最高起始磁导率,α相的体积份数为64%-70%,尺寸为9.4-11.0nm,含Si量约为16-19(at)%,此时,合金中Nb含量为3-5(at)%.  相似文献   

5.
采用有机溶剂体系中的化学共沉淀法,制备了纳米尺度的、具有高电化学活性的Al取代α-Ni(OH)2,并用XRD和FTIR光谱表征了它们的结构;通过考察样品在强碱性介质中的结构稳定性,探讨了Al含量对α-Ni(OH)2结构及电化学性能的影响.结果表明:当Al含量为7.5%、13.2%和17.2%时,样品的晶粒度分别为5.4、6.9和11.0nm.Al含量为7.5%的样品为α-Ni(OH)2和β-Ni(OH)2的混合结构,而Al含量为13.2%和17.2%的样品则为纯α-Ni(OH)2的单相结构.随着Al含量的增加,样品的结晶度增大,因而其稳定性增加,放电中点电位升高,电化学容量增大.  相似文献   

6.
准确测量声波在不同类型岩心中的传播速度是岩心声学性质分析的基础。一般实验室利用超声波透射法所测试的岩心样品均为小尺寸岩心样品。在测量小尺寸岩心样品横波波速时,难以消除的纵波余震信号会对横波的识别产生干扰。提出了一个在实验室内测量小尺寸岩心样品中横波波速的"辅助块"超声波透射波测试方案,较好地实现了纵横波的分离,减小了横波波速的测量误差,提高了岩心样品横波波速测试的精度。给出了上述测量方案和测量实例分析,该方法亦可用于一般固体样品中横波波速的测量。  相似文献   

7.
系统研究了(Nd0.75Na0.25)1-x(Nd0.5Ca0.5)xMnO3(x=0、0.25、0.5、0.75、1)单相多晶样品在低温下的电磁输运性质和超声特性.电阻和磁化率的测量表明所有样品均发生了电荷有序相变.随着钠掺杂量的增加,电荷有序相变温度(Tco)向低温移动同时低温端磁化强度增大,并且电荷有序态趋向于不稳定和短程化.超声纵波声速从室温开始随着温度的降低逐渐减小,在Tco之后声速急剧硬化.这种超声异常表明体系中存在着强烈的电-声子相互作用,该电-声子耦合来源于Mn^3+的Jahn-Teller效应.对纵波模量软化部分的拟合显示,随着钠的掺入,反映Jahn-Teller效应大小的Jahn-Teller耦合能EJT变小.分析认为电荷失配效应是导致电荷有序被抑制和Jahn-Teller耦合能EJT变小的主要因素.  相似文献   

8.
测定了体积含量Vf不同(5.4,9.1和13.6%)的Al2O3短纤维增强的铝基复合材料的纵波声速,横波声速和密度,并由此得出它们的切变模量μ和杨氏模量E,结果发现,随Vf增加,纵波声速减小,横波声速增加,与纯铝相比,μ和E均明显增大,还给出纵波超声声速和超声衰减在100~300K温区内的温度响应曲线。  相似文献   

9.
采用铜模上吸铸法制备了低成本的Fe78-2xCrxMoxSn2P10Si4B4C2(x=2、4(原子分数),以下同)铁基块体非晶合金,通过失重法和电化学方法测量了该系列块体非晶合金的耐腐蚀特性,发现该合金系列具有较强的耐腐蚀能力:对x=2和4的样品在3.5%的NaCl溶液中浸泡45d后的腐蚀速度分别约为0.021和0.019m/n]a,比MSI 304L不锈钢(0.046mm/a)具有更好的耐蚀性;对在不同浓度(1、3、6N)HCl溶液中的极化曲线测量发现,两种试样在极化过程中均出现钝化的现象,并存在一较宽的钝化区,钝化区范围随着HCl溶液浓度的增大而逐渐变窄。初步分析认为,该合金系列高的耐腐蚀性能源自于非晶结构自身的特征及其特殊的成分组成。  相似文献   

10.
骨质疏松发生时,人体皮质骨层的孔隙度将增大。为研究皮质骨参数(厚度、横波速度、纵波速度)与骨质疏松症的关系,文章利用有限元方法对不同孔隙度(0∶3%∶27%)的单层皮质骨进行仿真,以3个周期的高斯包络正弦波作为激励,将采集到的超声导波信号先后经过二维傅里叶变换和Burg算法处理后得到频散数据,与基于FloquetBloch理论建立的理论频散曲线数据库进行匹配反演,得到皮质骨厚度、横波速度、纵波速度参数。结果显示皮质骨厚度反演准确,皮质骨孔隙度与横波速度和纵波速度呈负相关,横波速度敏感度为19.0%,纵波速度敏感度为5.5%。横波速度敏感度更高,临床诊断潜力更大。并对6组牛胫骨进行了离体实验,结果显示,反演得到的皮质骨厚度与其实际测量值的平均相对误差为4.0%,且实验频散曲线与理论频散曲线相吻合,验证了文中算法在真实皮质骨参数反演上的可行性和准确性。文中的研究在骨质疏松超声检测中具有应用潜力。  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
13.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

14.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

15.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

16.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

17.
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill.  相似文献   

18.
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...  相似文献   

19.
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.  相似文献   

20.
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...  相似文献   

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