Nature of (001) and (001) faces and flocculation flotation of kaolinite

Flotation mechanism of kaolinite was investigated through flotation test, SEM analysis and quantum chemical simulation calculation. It is shown that the (001) face of kaolinite easily adsorb cationic collector to exhibit hydrophobicity; the (001) face is easily interacted with the reagent carrying the group of high electronegativity (-O-,-N-, F-) to show hydrophilicity. The cationic and anionic polyacrylamide are adsorbed onto the (001) face of kaolinite and the flocculation of kaolinite particles may take place; the (001) faces are exposed to interact with cationic collector to be rendered hydrophobicity. Thus, the macromolecules can evidently enhance the flotation of kaolinite in alkaline media.     

Nature of (001) and (00) faces and flocculation flotation of kaolinite

1　INTRODUCTIONThediasporicbauxiteresourceinChinaischar acterizedbyhighcontentofAl2 O3andSiO2 andlowmassratioofAl2 O3toSiO2 ,theratioisusually 5 8.ThediasporicbauxitewithlowmassratioofAl2 O3toSiO2 cannotbedirectlyprocessedbyBayer’stechnol ogy .ThesinteringorcombinationofsinteringandBayerprocessareoftenusedtotreatsuchdiasporicbauxite ,showingenergy intensiveandenvironmentalunfriendly[1] .ItisrequiredtoincreasethemassratioofAl2 O3toSiO2 toabove 10byphysicalseparationsothattheBayer…     

叔胺在高岭石（001）面吸附的分子动力学模拟

三种叔胺（DRN,DEN,DPN）对高岭石的捕收能力顺序为：DEN〉DPN〉DRN。Zeta 电位测试表明,这三种叔胺能显著增大高岭石的表面电位,对表面电位的增大同样遵循顺序：DEN〉DPN〉DRN。分子动力学模拟研究表明,叔胺阳离子在吸附到高岭石（001）面的过程中,N 原子上所连接的取代基的空间形状发生了偏转或扭曲,相关键角发生了变化。结合量子化学计算结果进行综合计算可知,这三种叔胺阳离子与高岭石 4×4×3 的（001）面的库仑静电力分别为：1.38×10-7 N （DRN12H＋）,1.44×10-6 N （DEN12H＋）,1.383×10-6N（DPN12H＋）。     

变性淀粉在铝硅矿物浮选分离中的作用机理

通过浮选实验、动电位和红外光谱测定,详细考察了变性淀粉在铝硅矿物浮选分离中的作用效果和机理。浮选实验显示：非离子淀粉和阴离子淀粉在pH＜6时,抑制一水硬铝石的浮选,但当pH＞6时,却对一水硬铝石浮选有活化作用;阳离子淀粉在较宽pH值范围内对一水硬铝石均有抑制作用;3种淀粉化合物在pH＜6时均活化高岭石的浮选,当pH＞6时活化作用较微。结果表明：变性淀粉是一水硬铝石型铝土矿反浮选中实现一水硬铝石和高岭石分离的有效调整剂,阴离子淀粉使矿物表面ζ电位更负,阳离子淀粉使矿物质表面ζ电位更正,非离子淀粉使矿物表面电位绝对值减小。由实验结果结合药剂与矿物作用前后的红外光谱分析,得出结论：非离子淀粉主要通过氢键作用吸附于矿物表面,而静电力和化学键合力在阴离子淀粉和阳离子淀粉吸附中发挥着重要作用。     

N-(3-氨丙基)-月桂酰胺对铝硅酸盐矿物的浮选

研究了N-(3-氨丙基)-月桂酰胺对高岭石、伊利石和叶蜡石的浮选性能。结果表明：N-(3-氨丙基)-月桂酰胺对这些铝硅酸盐都有较好的捕收性能，对高岭石、伊利石和叶蜡石的回收率分别在91％，90％和96％以上。矿浆pH值对3种矿物的可浮性影响较小，在一个较宽的pH范围内，3种矿浆的Zeta电位均为负值，矿粒表面荷负电。红外光谱证明，3种矿物中均含有-OH基。酸性介质中，捕收剂分子通过静电引力吸附在矿粒表面；碱性介质中，捕收剂分子通过氢键吸附在矿粒表面。矿粒的扫描电镜照片表明：叶蜡石颗粒主要呈薄片状；伊利石和高岭石颗粒晕不规则形状。     

WELL-DISPERSED NANODIAMOND AQUEOUS SUSPENSIONS ——PREPARATION, PROPERTIES AND APPLICATIONS

Well-dispersed nanodiamond(ND) aqueous suspensions in both acidic and alkaline environments is prepared by mechanochemical treatment. All the ND particles in the suspensions are smaller than 100nm in dimension with a narrow size distribution, and no destabilization phenomena were detected in a duration of more than one year. Stable. dispersion of ND in the media may attributed to the strong electrostatic repulsion between particles because of the adsorption of dispersants, while mechanical forces may strengthen this adsorption reaction. Good adaptability and applicability of the suspensions to the change of ND concentration and surrounding temperature are observed, and improved performances of ND diamonds are obtained when used in uhrafine polishing and composite plating.     

Flotation of aluminosilicate minerals using alkylguanidine collectors

The flotation mechanism of aluminosilicate minerals using alkylguanidine collectors was studied through flotation experiments, Zeta potential measurements and FT-IR spectrum analysis. It is shown that kaolinite, illite and pyrophyllite all exhibit good floatability with alkylguanidines as collectors at pH 4-12. The flotation recoveries rise with the increase of the carbon chain length. Isoelectric point(IEP) is determined to be 3.5, 3.0 and 2.3 for kaolinite, illite and pyrophyllite, respectively. However, it is anomalous that the presence of cationic collectors has less influence on the negatively charged mineral surfaces. It is explained by the special structure of guanidine which is one of the strongest bases, having two -NH2 groups. One of them maybe interacts with minerals by electrostatic forces, and the other maybe forms hydrogen bonding with OH- ions on the aluminosilicate surfaces or in the aqueous solution, increasing the density of negative charge on the aluminosilicate surface and leading unpronounced positive charge to increase on the aluminosilicate. By combining the flotation tests, Zeta potential and FTIR measurements above, the interaction mechanism can be concluded. The simultaneous presence of cationic and neutral amine groups makes it possible for SAG cation to bind on three aluminosilicate minerals by both electrostatic attraction and hydrogen bonding. While in acidic medium, the interaction of the alkylguanidines on the aluminosilicate surfaces is mainly by means of electrostatic force and hydrogen bond; in the alkaline medium, it is by the way of electrostatic effect and hydrogen bond.     

DISLOCATION PINNING IN HIGH TEMPERATURE DEFORMED Ni3(Al,Ti) SINGLE CRYSTALS CONTAINING DISORDERED γ PRECIPITATES

A transmission electron microscopy (TEM) investigation has been performed on the dislocation pinning in LI2-ordered Ni3(Al, Ti) containing disordered γ precipitates. The morphology of deformation induced dislocations in the γ' base alloys containing fine dispersion of disordered γ was investigated by means of weak-beam electron microscopy. The superdislocations are strongly attracted to the disordered particles and dissociate on the (111) plane in the γ particles, while they dissociate on the (010) plane in the γ' matrix. The disordered γ precipitates play an important role as a pinning point during the cross-slip of superdislocations from (111) to (010) planes in the γ'matrix and restrain the cross-slip of superdislocations. The interaction of superdislocations with disordered particles causes the formation of superkinks, jogs and closed loops.     

POSS在无铅焊点中界面反应能的分子动力学模拟

运用分子动力学模拟研究了环己烯POSS在无铅焊点锡(β-Sn)晶体的(100)、(110)、(001)面以及在Sn-Ag-Cu合金表面的界面反应,得到了各自的界面反应能大小.结果表明,环己烯POSS易与β-Sn的各主要晶面相结合,但在(110)面上具有最低的界面反应能,结合性能最好.在锡中加入银(Ag)和铜(Cu)提高了环己烯POSS在其表面的界面反应能,表明对结合性能产生了不利影响,但仍然具有较好的结合性能.此外,还计算了环己烯POSS的溶解度参数.对于理解POSS对于无铅焊点的增强作用以及应用POSS来开发焊料增强剂具有重要而实际的意义     

高岭石层间原位合成纳米银及其表征

以高岭石-二甲基亚砜作为前驱体,PVP(聚乙烯吡咯烷酮)作分散剂,银氨络合物层间取代,以高岭石的层间作为反应器来控制银粒子的大小,制备出Ag/高岭石复合物.XRD表明,PVP对高岭石进行了表面改性,促进了纳米银粒子在层间的合成,出现明显的Ag的(111)、(200)、(220)、(311)4个衍射峰.根据小角度Ag的(001)衍射峰可知,高岭石层间距由0.716nm被扩大到4.53nm.TEM直观地表现了银在高岭石层间的形貌.     

WELL-DISPERSED NANODIAMOND AQUEOUS SUSPENSIONS——PREPARATION,PROPERTIES AND APPLICATIONS

1　INTRODUCTIONAsitwassynthesizedundertheconditionofhightemperatureandhighpressure ,andowingtothecommoncharacteristicsoffinedimensionandhighsurfaceenergyofnanoscaledparticles ,nanodiamond (ND )preparedbydetonationexplosioncaneasilyformstrongaggregates WhenNDpowderwasaddedinaqueousmedia ,obviousaggregationandsedimentationcanbeobserved ,whichimpairsitscharacteristicsasananometerparticle ,andthushindereditsapplication Inthiscase ,stabledispersionofNDinaqueousmediaisofgreatimportance[1 4 ] …     

HRTEM and EELS studies of defects structure and amorphous-like graphite induced by ball-milling

Deformation structures and amorphization kinetics of graphite with high crystallinity upon ball-milling (BM) are studied by high-resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS). Basal plane stacking disorder, cleavage, delamination cracks, misorientation bands and low-angle (0002) twist boundaries are observed. The basal plane stacking disorder is probably produced by simultaneous shearing of all the lattice planes involved. Other defects such as half Frank loops or interstitial loops and significant bending and buckling of the basal planes are also frequently observed. Sustained shearing of (0002) planes acting in parallel with the increase of the Frank loops finally leads to the breakage of the hexagonal network in a very fine scale until an amorphous-like structure results. Although the amorphous-like phase exhibits amorphous halo diffraction patterns, HRTEM investigations indicate that it consists of highly curled small flakes with average basal plane diameter less than 5 nm and thickness (normal to the basal planes) less than 2 nm. EELS investigations demonstrate that its bonding is essentially sp². The present study clarifies the defect configuration appearing in heavily deformed graphite and also shows evidence that the amorphization of graphite is a defect-controlled process.     

Dislocation structure of cementite in granular pearlite after cold plastic deformation

Cementite microstructure of the U8 steel with a granular pearlite structure has been investigated by the method of electron microscopy. It has been established that, at the early stages of deformation, carbide particles are deformed through the movement of stacking faults, which are characterized by an α[010] partial shift in the (001) planes of cementite. The Burgers vector, the slip plane [010](001) of the split dislocations forming pileups, and deformation bands have been determined using gb analysis. The stacking fault energy has been estimated in a (001) cementite plane: γ_sf ～ 12.8 mJ/m². With increasing degree of deformation, an additional slip has been shown to occur in cementite by the system [100](011).     

晶体相场法模拟纳米晶体的单向拉伸变形

通过籽晶法控制晶体取向,研究了双晶镍基高温合金AM3胞状枝晶界面定向凝固过程中的双晶竞争生长.结果表明,两籽晶<001>取向的相对位置对晶粒竞争生长有很大的影响.双晶<001>取向在不同平面时,晶粒竞争生长的主要方式是通过物理阻挡,在晶界处处于阻挡优势的晶粒在竞争生长中胜出.对双晶的<001>取向在同一平面时,两籽晶以大角度背离发散生长时,在双晶的发散区容易生成杂晶.     

Interactions between whey proteins and kaolinite surfaces

The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption–desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein–kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered.     

单晶镍基合金在拉伸蠕变期间的组织演化与分析

通过[001]取向镍基单晶合金拉伸蠕变期间的组织形貌观察,采用应力应变有限元方法计算出立方γ/γ′两相共格界面的vonMises应力分布,研究了合金在蠕变期间γ′相的定向粗化规律。结果表明,施加拉应力可改变立方γ/γ′两相的应力分布,使不同晶面发生晶格收缩与扩张应变,其中,(001)晶面产生晶格收缩可排斥较大半径的Al、Ti原子,(100)和(010)晶面沿平行于应力轴方向产生晶格扩张应变,可诱捕较大半径的Al、Ti原子,是使其γ′相沿扩张晶格的法线定向生长成为类似筛网层状结构的组织演化规律。并进一步提出蠕变期间发生元素扩散和γ′相定向生长的驱动力。     

AZ31镁合金蠕变初期的变形特征

通过蠕变曲线的测定和TEM的形貌观察,研究了AZ31镁合金在蠕变初期的变形特征及组织演化规律．结果表明,蠕变初期的变形特征是：大量形变产生的(α)位错在合金的基面和非基面滑移,(α c)位错在锥面滑移．其中(α)位错通过位错分解反应可由一非基面交滑移至另一非基面．随蠕变进行,高密度的形变位错发生动态回复,可进一步束集形成位错胞和位错墙．蠕变初始阶段,在应力的作用下,适当取向的晶体发生孪生,并作为一种附加的变形机制而改善合金的韧性．     

高岭石对氰化浸金的影响及助浸研究

采用电化学实验研究了在氰化浸金过程中常见矿物高岭石对金溶解速率及对溶液中金的吸附效果的影响。结果表明,高岭石的存在会使金的溶解速率加快,随着高岭石粒度逐渐降低金的溶解速率提高,且高岭石对溶液中金的吸附率增加。氰化浸出实验结果表明,高岭石存在时金的浸出率由93.21%降低到91.76%,采用柠檬酸三钠、过氧化镁和十二烷基硫酸钠助浸时,金浸出率升高至94.42%。能谱分析(EDS)发现浸出物中高岭石表面有金元素存在,表明高岭石会吸附溶液中的金。红外光谱分析和密度泛函理论计算表明,高岭石与金发生化学吸附作用,氢原子为高岭石的活性位点,C6H5O7^3-会优先吸附于高岭石(001)表面,加入助浸剂可降低高岭石与金的吸附强度,提高金的浸出率。     

DEFORMATION-INDUCED α2→γ TRANSFORMATION IN A HOT DEFORMED Ti-45A1-10Nb ALLOY

1.IntroductionTwo-phase(a2 7)TiAl-basedall0ysarecurrentlyunderextensiveinvestigationbe-causetheirmechanicalpr0pertiesaresuperi0rtoeitherthesinglephasecr20rtheryall0ysl1].Themicrostructureofthetwo-phasealloyswasf0undtohaveastronginfluence0ntheme-chanicalpr0pertiesI2].Themainmicrostructuralcharacteristics0ftheall0yswithlamellarstructurewhichconsistsofalternatinglayers0f0rdered7anda2lamellaewiththecri-entationrelati0nship{lll}./(OOO1)..3<11O>./<1120>.,)havebeenstudiedindetailbymanyinvestigat0r…     

Interface mobility in Ni49.8Ti42.2Hf8 shape memory alloy

The ternary Ni_49.8Ti_42.2Hf₈ shape memory alloy shows mechanical peculiarities compared with NiTi alloy. These are linked to (i) the distortion of the habit plane of the ternary alloy and (ii) the observed (001) mechanical twinning, which helps to accommodate plastic deformation in Ni_49.8Ti_42.2Hf₈ and not in NiTi alloy. The distortion of the habit plane limits its mobility, evidence of which being brought here by internal friction. The (001) mechanical twinning causes the appearance of a very thin microstructure in martensite laths deformed by tension. A model is proposed as a possible mechanism giving birth to this supplementary mechanical twinning: repeated slips by a/2 on (001) planes would create translative (001) micro-twins coherent with the observed microstructure. These micro-twins may be produced by the dissociation of dislocations with the Burgers vector a.