全尾砂速凝固化胶结充填新工艺的试验研究

本文叙述了一种金属矿山全尾砂速凝固化胶结充填新工艺。该工艺使用“高水速凝固化充填材料”作固化胶结剂。这种材料分为甲乙两种,使用时,分别与全尾砂浆制成两种浓度分别为30％、70％的充填料浆输送到井下,经混合器混合后充入采场,在2小时内,不用脱水便可以凝结为固态充填体,8小时后便可以上设备作业。新工艺的试验成功解决了胶结充填作业中分级尾砂制浆复杂、高浓度输送困难、需井下脱水、不易平场和接顶等一系列难题。该工艺简单、效率高、效益好。

高水速凝固化材料的性能及其水化硬化机理研究

本文研究了一种新型胶凝材料──以ＣＡＳ水泥熟料为基料的高水速凝固化材料的水化硬化机理和水化产物组成以及水化温度、石膏掺量对其凝结、强度性能的影响。同时还初步探讨了这种材料在土壤固化中的应用。研究结果表明，含Ｃ＿４Ａ＿３Ｓ的ＣＡＳ的水泥熟料浆体与另一种含有石膏、Ｃａ（ＯＨ）＿２、石灰石、悬浮剂和某种碱金属盐的浆体能在较短时间内发生化合作用并形成大量的钙矾石等水化产物，导致该材料在水固比高达２．０～３．０时迅速胶凝、硬化并产生一定的强度；这种材料的石膏掺量有一较佳范围，其性能在环境温度低于３０℃时发挥较佳；同时发现这种材料对含水率很高的泥浆固化效果明显优于Ａｕｇｈｔ—Ｓｅｔ固化剂。

Effect of cooling rates on clustering towards icosahedra in rapidly solidified Cu_(56)Zr_(44) alloy

The rapid solidification processes of liquid Cu56Zr44 alloys at different cooling rates （γ） were simulated by a molecular dynamics （MD） method. In order to assess the influence of cooling rate on the clustering tendency and degree towards icosahedrons, a ten-indices＇ cluster-type index method was suggested to characterize the local atomic structures in the super-cooled liquid and the rapidly solidified solid. And their clustering and ordering degrees as well as the packing density of ieosahedral clusters were also evaluated by an icosahedral clustering degree （fI）, the chemical order parameter （ηαβ） and densification coefficients （D0, DI and DIS）, respectively. Results show that the main local atomic configurations in Cu56Zr44 alloy system are Z12 clusters centered by Cu, and most of which are （12 0 12 0 0 0 0 0 0 0） standard icosahedra and （12 0 8 0 0 0 2 2 0 0） as well as （12 2 8 2 0 0 0 0 0 0） defective icosahedra. Below glass transition temperature （Tg）, these icosahedral clusters will be coalesced to various icosahedral medium-range orders （IMROs） by IS linkages, namely, icosahedral bond, and their number N, size n, order parameter ηαβ as well as spatial distributions vary with y. As the cooling rate exceeds the critical value （γc） at which a glassy transition can take place, a lower cooling rate, e.g., γ1=10^1K/ns, is demonstrated to be favorable to uplift the number of icosahedra and enlarge the size of IMROs compared with the higher cooling rates, e.g., γ5=10^5 K/ns, and their packing density and clustering degree towards icosahedra in the rapidly solidified solid can also benefit from the slow cooling process.

Influence of rapid solidification on Sn-8Zn-3Bi alloy characteristics and microstructural evolution of solder/Cu joints during elevated temperature aging

The effects of rapid solidification on the microstructure and melting behavior of the Sn-8Zn-3Bi alloy were studied. The evolution of the microstructuraI characteristics of the solder/Cu joint after an isothermal aging at 150 ℃ was also analyzed to evaluate the interconnect reliability. Results showed that the Bi in Sn-8Zn-3Bi solder alloy completely dissolved in the Sn matrix with a dendritic structure after rapid solidification. Compared with as-solidified Sn-8Zn-3Bi solder alloy, the melting temperature of the rapid solidified alloy rose to close to that of the Sn-Zn eutectic alloy due to the extreme dissolution of Bi in Sn matrix. Meanwhile, the adverse effect on melting behavior due to Bi addition was decreased significantly. The interfacial intermetallic compound （IMC） layer of the solder/Cu joint was more compact and uniform. Rapid solidification process obviously depressed the formation and growth of the interfacial IMC during the high-temperature aging and improved the high-temperature stability of the Sn-8Zn-3Bi solder/Cu joint.

AgNi15 composite particles prepared by ultrasonic arc spray atomization method

Ultrasonic arc spray atomization (UASA) method was used to prepare high-melting-point, immiscible AgNi15 (mass fraction, %) composite particles. Sieving was used to determine the size distribution of the AgNi15 particles. The morphology, rapidly solidified structure and metastable solution expansion of the AgNi15 particles were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), respectively. The results show that the AgNi15 composite particles are spherical and well-dispersed, and the mass fractions of the particles with diameters <74μm and <55 μm are 99.5% and 98%, respectively. The rapidly solidified structure of the AgNi15 particles consists of spherical nickel-richβ(Ni)-phase particles dispersed throughout a silver-richα(Ag)-phase matrix andα(Ag)-phase nanoparticles dispersed throughout largerβ(Ni)-phase particles. The silver and nickel in the AgNi15 particles form a reciprocally extended metastable solution, and the solid solubility of nickel in the silver matrix at room temperature is in the range of 0.16%?0.36% (mole fraction).

Dendritic growth and solute trapping in rapidly solidified Cu-based alloys

Rapid solidification of binary Cu-22%Sn peritectic alloys and Cu-5%Sn-5%Ni-5%Ag quaternary alloys was accomplished by glass fluxing, drop tube and melt spinning methods. The undercooled, by glass fluxing method, Cu-22%Sn peritectic alloy was composed of a（Cu） and δ（Cu41Snll） phases. If rapidly solidified in a drop tube, the alloy phase constitution changed from α（Cu） and δ（Cu41Sn11） phases into a single supersaturated （Cu） phase with the reducing of droplet diameter, and the maximum solubility of Sn in （Cu） phase extended to 22%. The Cu-5%Sn-5%Ni-5%Ag quaternary alloy was composed of （Cu） and （Ag） phases under the containerless processing condition in a drop tube, and the solute microsegregation of （Cu） phase was obvious. When the Cu-5%Sn-5%Ni-5%Ag quaternary alloy was solidified by melt spinning method, microsegregation was suppressed and solute trapping occurred. The experimental results show that the microstructures of primary （Cu） phase in the two alloys transfer from coarse dendrites into equiaxed grains with the increase of cooling rate and undercooling, which is accompanied by the grain refinement effect.