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.     

DISPERSION OF NANODIAMOND IN AQUEOUS SYSTEM

The effect of Chemical Mechanical Modification (CMM) and dispersants on the ζ-potential of nanodiamond particles in aqueous system and/he influence of the ultrasonic or shearing techniques on its size distribution were studied. CMM and the addition of dispersants AD-2 and AD-8 improve the stability of its suspension. With ultrasonic time prolonged, the mean average size of nanodiamond decreases, while with the prolongation of sheafing time, its mean size decreases first, then increases a lit tle. In the speed range used, the mean size decreases with the rising speed. If the whole ultrasonic time kept constant, it is better to add the dispersants before ultrasonic.     

PREPARATION OF NANO-CRYSTALLINE Fe-Cu THIN FILMS AND THEIR MAGNETIC PROPERTIES

Fe-Cu thin films of 0.2μm in thickness with different Cu contents were prepared by using r.f. magnetron sputtering onto glass substrate. The effect of sputtering param-eters, including Ar gas pressure and input rf power, on the structure and magnetic properties was investigated. It was found that when the power is lower than 70 W, the structure of the films remained single bcc-Fe phase with Cu solubility of up to 50at.%. TEM observations for the bcc-Fe phase showed that the grain size was in the nanometer range of less than 20nm. The coercivity of Fe-Cu films was largely affected by not only Ar gas pressure but also rf power, and reached about 2.5Oe in the pressure of 0.67-6.67Pa and in the power of less than WOW. In addition, saturation magnetization, with Cu content less than 60at. %, was about proportional to the con-tent of bcc-Fe. When Cu content was at 60at.%, however, saturation magnetization was much smaller than its calculation value.     

PROPERTIES, WELDABILITY AND APPLICATIONS OF ADVANCED WROUGHT SUPERALLOYS FOR GAS TURBINE ENGINES

Alloy selection and alloy design both require consideration of an array of material attributes, including in-service properties, weldability and fabricability. Critical properties of advanced wrought superaUoys for gas turbine applications include high temperature strength, thermal stability, oxidation resistance and fatigue resistance. In this paper, the properties of twelve wrought solid-solution-strengthened and six age-hardenable superalloys are compared. Weldability is an important attribute and can be a major limiting factor in the use of certain alloys. Weldability test methods are discussed and the resistance of alloys to solidification cracking and strain-age cracking is compared. The use of weldability testing in the development of modern wrought superalloys is discussed with several examples cited. Finally, alloy selection for gas turbine components is outlined, taking into account both alloy properties and fabricability.     

PREPARATION AND PROPERTIES OF THE MICRO-POWDER PHASE AND A NEW PHASE OF AMMONIUM TETRAMOLYBDATES

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PREPARATION OF Fe/Ni MULTILAYER FILMS AND THEIR MAGNETIC PROPERTIES

1. IntroductionAIllltili1},er ll1aterials attract l1lucll l1lore attelltioll[l--3I, because tlley provide a l1ewllletllod to desigll ll1aterials to lueet 1urio[[s requirelllellts. IIl additiol1, tlle developnlelltof electroll bea111 pl1}sical vapor deposi…     

MICROSTRUCTURE AND PREPARATION OF Ni,Al AND Fe NANOPOWDERS

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥＡＮＤＰＲＥＰＡＲＡＴＩＯＮＯＦＮｉ，ＡｌＡＮＤＦｅＮＡＮＯＰＯＷＤＥＲＳ①ＷｅｉＱｉｎａ，ｂ，ＬａｉＹｉｎｇｌｉｎｇａ，ＹａｎｇＨｏｎｇａ，ＬｉＣｈａｎｇｇｅｎｇａａＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＰｈｙｓｉｃｓａ...     

PREPARATION,PROPERTIES AND INTERFACE STRUCTURES OF Si_3N_(4w)/6061Al COMPOSITE

The Si_3N_4 whisker reinforced 6061Al composite with bending strength of 790 MPa wasprepared by squeeze casting process.After heat-treatment under T6 regime i.e.530℃,1 h solutioning and 160℃,24 h aging,an increment in strength and microhardnessmay be over 20% and 28% respectively,The microstructures of Si_3N_4 whisker andSi_3N_4/Al interface were observed by meas of HRTEM.The relation between interracialstructure and composite properties was discussed.     

Ti C N FILM PREPARATION AND ITS PROPERTIES BY LOW ENERGY CO-DEPOSITION ON STEEL

The Ti+C+N film was co-deposited on H13 steel by Filtered Vacuum Arc PlasmaDeposition (FVAPD) operated with a modified cathode. The co-deposited layer waseffective for the improvement of surface hardness and corrosion resistance. The nano-hardness value of the co-deposited film is 1.3 times more than that of undepositedsample. The corrosion behavior measurement shows that the corrosion resistance foracid corrosion and pitting corrosion was improved greatly. It is owing to the formationof the new ternary ceramic phase TiCo.7 No.3 in the co-deposited layer. The mechanismof property improvement is discussed.     

STUDY ON PREPARATION, COMPLEX PERMITTIVITY,PERMEABILITY AND MICROWAVE PROPERTIES OF BaZnZCo2-ZFe16O27／SiO2 MICROCRYSTALLINE GLASS CERAMICS

BaZnzCo2-zFe16O27/SiO2 microcrystalline glass ceramics with Z=0.0, 0.5, 0.8 and 1.1 were prepared at temperature 1200℃ for 5h by citrate sol-gel process. The complex dielectric constant and complex permeability of BaZnzCo2-zFe16 O27/SiO2-paraffin wax composites had been measured. Both the complex dielectric constant and dielectric loss exhibit almost no variation with frequency in 0.1-6.0GHz. The real part of permeability decreases with increasing frequency for all samples, and the imaginary part of permeability exhibits a clear resonance peak at 1.44GHz for Co2 W/SiO2, 1.32GHz for Zn0.5Co1.5 W/SiO2, 1.20GHz for Zn0.8Co1.2W/SiO2, and 1.08GHz for Zn1.1 Co0.9 W/SiO2. It is also showed that the content of zinc has a close effect on the magnetic properties of BaZnzCo2-zFe16O27/SiO2 microcrystalline glass ceramics, the greater the zinc content, the higher the values of imaginary part of permeability and magnetic loss.     

PREPARATION OF TiN FILMS BY N_2 ASSISTED Xe~+ ION BEAM ENHANCED DEPOSITION AND THEIR MECHANICAL PROPERTIES

A new method for preparation of hard TiN films has been developed by using electronbeam evaporation-deposition of Ti and bombardment with 40 keV Xe~+ ion beam ina N_2 gas environment.The synthesized TiN films were superior to PVD and CVDones in respects of improved adhesion to substrate and low preparing temperature.Theyexhibited good wear resistance and high hardness up to 2200 kg/mm~2.Some industrialapplications have been reported.     

MICROSTRUCTURE AND PROPERTIES OF Mn-CONTAINING TiAI ALLOYS

The microstructure of Ti-33wt-％ Al-(1.6-4.5)wt-％ Mn alloys are composed ofγ+α_2 phases,but the volume of x_2-phase is a little.Mn alloying decreases the latticeparameters a and c of γ-phase and the c/a ratio becomes nearly to one,because the atomicradius of Mn is less than the atomic radius of Ti or Al.Mn alloying promotes the formation oftwins in γ-phase and increases the ability of plastic deformation of TiAl alloys at room tem-perature.     

PREPARATION AND XRD STUDY OF LITHIUM DEFICIENT LiB COMPOUND

The LiB compounds in lithium deficient state were prepared by three methods and its crystal structure was investigated by using XRD. It is found that the lattice constant c of the compound will increase step by step with decreasing Li content from 0.2796nm of the normal LiB to 0.2886, 0.2981 and 0.3118nm of the lithium deficient LiB. The change of the lattice constant is reversible.     

MLCROSTRUCTURE AND PROPERTIES OF C-Cu NANOSTRUCTURE THIN FILM

1. IntroductionTlle filnls of dial11ol1d-Iike carboll (DLC) llave a smooth, chemically inert sllrface withhigh hardness, a sluall fri.ti.,1 coefficiellt, and a low threshold fOr electron emissioll. Theyllaxv lIlall}' applicatioIls ill differellt fields. T…     

MICROSTRUCTURE AND PROPERTIES OF HIGH BORON BEARING STEEL

1. IntroductionShieldi11g lnaterials play an ilnporta11t role iu the national defence a11d nuclear powerplal1ts. Recently, great efforts have bee1l 1nade on its developnlentll'2]. It's well known thatboron has pron1ising hot lleutrol1 absorptioll properti…     

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF NOVEL 718 SUPERALLOY

Recently, a novel 718 superalloy with remarkable structural stability at 680℃ has been designed and fabricated by CISRI (Central Iron and Steel Research Institute) etc. Phase identification of novel 718 alloy under the above-mentioned heat-treatment condition was performed using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Results show that the novel 718 alloy has outstanding structural stability at 680℃. The novel 718 alloy possess excellent structural stability and good mechanical properties, which is attributed to ?酌'-phase strengthening and also to the specific sandwich structure of the ?酌' ＋ ?酌' strengthening phase.     

PROCESSING AND PROPERTIES OF Nb_3Al ALLOYS

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MECHANICAL PROPERTIES AND MICROSTRUCTURES OF Ti(C,N) BASED CERMETS

ＭＥＣＨＡＮＩＣＡＬＰＲＯＰＥＲＴＩＥＳＡＮＤＭＩＣＲＯＳＴＲＵＣＴＵＲＥＳＯＦＴｉ（Ｃ，Ｎ）ＢＡＳＥＤＣＥＲＭＥＴＳ￥ＬｉｕＮｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅｒｉｎｇ，ＡｎｈｕｉＩｎｓｔｉｌｕｔｅ...     

DESIGN AND PREPARATION OF SILICON NITRIDE COMPOSITE WITH HIGH FRACTURE TOUGHNESS AND NACRE STRUCTURE

ＤＥＳＩＧＮＡＮＤＰＲＥＰＡＲＡＴＩＯＮＯＦＳＩＬＩＣＯＮＮＩＴＲＩＤＥＣＯＭＰＯＳＩＴＥＷＩＴＨＨＩＧＨＦＲＡＣＴＵＲＥＴＯＵＧＨＮＥＳＳＡＮＤＮＡＣＲＥＳＴＲＵＣＴＵＲＥＹＨｕａｎｇ；Ｈ．ＮＨａｏ；Ｙ．Ｌ．ＣｈｅｎａｎｄＢ．Ｌ．Ｚｈｏｕ（１）Ｄｅ...     

EFFECT OF Zr,Cr AND B ADDITIVES ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ni_3Al ALLOYS

The microstructure and the mechanical properties from room temperature up to 1050℃ ofNi_3Al alloys containing 0—0.6 at.-%Zr,0—7.7 at.-%Cr and 0—2.22 at.-%B have beenstudied.It was found that the temperature dependence of their yield strength variation revealsto be anomalous,i.e.the strength increases with the temperature raising,and then decreasestill it surpassed the peak value.Both Zr and Zr+Cr may improve the yield strength of the al-loys in the entire range of testing temperatures,as well as the tensile strength and elongationunder high temperatures.B is favourable to raise the tensile and yield strengths of the alloys,and also plasticity.But the strength will reduce as B added is over 2.22 at.-%.TheNi_(20)Al_3B_6 and Ni_3Al eutectic mixture like islands and globes precipitated inside the grainsand along the grain bounderies,which are harmful to the strength and ductility,may beformed when the B content exceeds the limit of solubility.