The effect of deep cryogenic treatment on microstructure and carbon partition behavior of high carbon high alloy tool steel SDC99, which had been tempered at different temperatures was investigated by three-dimensional atom probe and internal friction combined with the hardness testing. The results show that the hardness of SDC99 steel significantly increased after deep cryogenic treatment. The hardness of SDC99 sample after deep cryogenic treatment is 2 HRC higher than the quenching sample, while the hardness of sample subjected to deep cryogenic treated and then tempered at 200^oC is 1.5 HRC higher than the conventional heat treated sample. The enlargement of the Snoek-Kê-K?ster (SKK) peak height indicates stronger interaction between the interstitial carbon atoms and dislocations after deep cryogenic treatment. In comparison to the merely quenched sample, the dislocation density of the quenched and deep cryogenic treated sample increased by 17%. The extent of carbon segregation was enhanced significantly after deep cryogenic treatment. The peak of the carbon atom concentration in carbon-rich regions of SDC99 steel after quenched, deep cryogenic treated, quenched and then tempered at 200℃, deep cryogenic treated and then tempered at 200^oC are 2%, 8%, 8% and 15% (atomic fraction) respectively.

Q550 steel was welded by shielded metal arc welding with varying heat inputs, and then the microstructure of the weld joint was characterized, while the effect of strain rate on its mechanical behavior were examined. The results show that when the heat input below 18 kJ/cm, with the increasing heat input, acicular ferrite content of the fusion zone and the grain size of the heat affected zone increased. With the increasing strain rate, the elongation and tensile strength of the welded joint increased to different extents. With the increasing heat input, the depth of large dimples increased, while the area of small dimples decreased in the fractured surface. During high speed tension, the resistance to dislocation slip increased, however the propagating rate of dislocation slip far behind the increasing speed of load, which led to increase in yield strength and tensile strength with the increase of strain rate. With the increasing heat input, acicular ferrite content of fusion zone increased, which is the main reason for the increase of sensitivity of tensile property to strain rate.

The effect of aging processes on the tempered microstructure and mechanical properties of the forged AerMet100 steel was investigated, while the named processes include normal aging, pre-aging + normal aging and double aging etc. The results show that high tensile strength (1978 MPa) with low impact toughness (A_K=74 J) can be obtained by the normal aging process; higher impact toughness (impact energy 102 J) can be obtained by double aging process, but tensile strength is lower (1662 MPa); however, excellent strength and toughness (σ_b=1946 MPa; A_K=104 J) can be obtained by pre aging + normal aging (510℃×30 min, OQ+482℃×5 h, AC) process. The improvment of strength and toughness can be attribute to that the 510℃ pre aging could promote the C atom diffusion, therewith increased the amount and the stability of the flim-like reversed austenite; besides enable the M₂C precipitate to maintain a good lattice relationship with the matrix induced by the short time (≤30 min) pre aging, therefore the precipitation strengthening effect was enhanced.

For improving the heavy metal ion chelating ability of chelatingheavy metal ions and the microbiological stability of chitosan (CS), L-arginine (L-Arg) was immobilized on CS molecules, in presence of condensing agent 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl) and coupling reagent N-Hydroxysuccinimide (NHS), using chitosan as a matrix, a new kind of natural-macromolecular-based heavy metal ion chelating material, L-arginine GRafted Chitosan (CA)of chelating heavy metal ions, was prepared by grafting L-arginine (L-Arg) onto CS molecules, with chitosan as raw mate-rial, 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl) ascondensing agent and N-Hydroxysuccinimide (NHS) coupling reagent. The GRafting mechanism was deeply discussed and the GRafted conditions were optimized by signal factor experiments. The structure and composition of the product were characterized by elemental analysis, infrared spectrum (FT-IR), Raman spectra (RAM) and x-ray diffraction (XRD). Then, the processing parameters were optimized via experiments with single factor. The results show that a grafting ratio (GR) of 16.85% may be acquired when the for the following parameters: molar ratios of reagents CS:Arg:EDC =1:1:1 and EDC:NHS =3:1, reaction time 12 h and pH=5, the GRating ratio (GR) was up to 16.85%. By adjusting the ratio of reactants, products with different GR levels could be obtained. The results of adsorption experiments showed CA (GR=16.85%) had higher removalefficiency of high-concentrated Cu²⁺ and Ni²⁺ ions than CS.CA also possessedhigher antibacterial property compared with CS, whilst the CA with 16.85% GRof was up to 16.85%, it can almost completely inhibited the growth of colibacillus and staphylococcus aureus.

The effect of over-aging process on mechanical properties and hydrogen permeation behavior of a cold-rolled model low carbon steel sheet for enameling was investigated by means of a continuous annealing simulator, which aims to simulate the over-aging process in continuous annealing line in steel works. It was found that the cementite precipitates within grains became finer but possessed large volume fraction in the steel sheet annealed with the slow cooling over-aging process, in the contrast to the conventional isothermal over-aging process. The strength of sheets annealed with the slow cooling over-aging was slightly lower but with significantly enhanced elongation . With the increasing effect of hydrogen traps due to the higher amount of finer precipitates of cementite within ferrite grains, the hydrogen diffusion in the steel was hindered. The hydrogen diffusion coefficient, D_L for the sheet annealed with using slow cooling over-aging process was reduced by approx. 18% in comparison with those with the conventional isothermal over-aging process. Therewith, the mechanical property and fish-scaling resistance of the low-carbon cold-rolled steel sheet for enameling can be significantly improved by this improved over-aging process.

The microstructure and precipitates of the creep-ruptured and aged alloy 617B at 750^oC were characterized by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The polygonal (or strip-type) M₂₃C₆ particles with a complex face-centered cubic (fcc) structure locate along grain boundaries and inside grains, and granular γ ′ phase particles with an ordered fcc-structure inside grains were observed during creep and aging. The precipitates grown up with test time. The comparative observation of the aged and creep-ruptured alloy samples revealed that the applied stress did not affect the growth of γ ′ phase obviously, but affect the precipitation of carbides at grain boundaries greatly. The stress leads to the sharp growth and agglomation of M₂₃C₆ particles after a long time creep test.

The evolution of radial texture and microstructure of Cu-Nb microcomposite wires was investigated using scanning electron microscopy with electron back-scattering diffraction. Cu matrix shows a major <111> fiber texture, and the intensity of which increases from the surface to the center; Nb phase, however, shows a major <110> fiber texture without significant change in the intensity along the radial direction. The microhardness is determined by both the interface area density and <111>Cu texture. The texture hardening is the dominant influence on the change of radial microhardness.

Tea polyphenols and aluminum flakes was utilized as the reductants to reduce graphene oxide and then synthesize graphene, the as-prepared graphene was then to prepare the graphene-based conductive paper recombination with cellulose. The influence of composite ratio between cellulose and graphene, the conductive paper ration, the folding times and angles to the conductive paper’s electrical property were discussed. The results show that graphene oxide can be reduced effectively by tea polyphenols and aluminum flakes, the sp²structure can be restored effectively. The optimal conditions is composite ratio between cellulose and graphene 1:1, the conductive paper ration 72 g/m², the sheet resistanceand elasticity modulus of the as-prepared conductive paper is 66.33 Ω/sqand 1234.00 MPa. The conductive paper reserved good conductivity after 500 times folding and different folding angles, the ratio between after-folded resistanceand initial resistance is near 1.0. Besides, the specific capacitance of the conductive paper is 5.47 mF/cm², which suggests a good capacitive performance.

Cu₂ZnSnS₄ (CZTS) particles were synthesized by a facile solvothermal method in polyvinylpyrrolidone (PVP) containing alcohols solvent, with CuCl₂2H₂O, Zn(Ac)₂2H₂O and SnCl₄5H₂O as metal precursor, and thiourea as sulfur source, respectively. The effect of the variation of solubility parameter of alcohols solvents on crystal structure, composition, morphology and absorption spectra of the synthesized CZTS particles were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy(EDS), UV-Vis spectroscopy and electrochemical analyzer. The results reveal that the solubility parameter of alcohols solvent has a certain influence on the crystallization, morphology, atomic ratios and photoelectric properties of the as-synthesized CZTS particles. The optimum alcohols solvent is ethylene glycol.The crystallization of CZTS particles synthesized under the above condition is pure and complete, and the CZTS particles with flaky facets are uniform and mono-dispersed. The atomic ratio of elements for CZTS particles is close to stoichiometric coefficient and the band gap of the products is about 1.47 eV, which is close to the optimum value for solar photoelectric conversion. The resistivity of CZTS is 45.86 Ωm.

Mono-dispersed polystyrene microspheres were prepare by UV irradiation assisted polymerization of styrene monomer with AgCl nano-cubic particles as photoinitiator and polyvinylpyrrolidone (PVP) as dispersion stabilizer. The morphology, molecular structure and glass transition temperature of the polymers were characterized by SEM, FT-IR and DSC respectively. From the polymerization dynamics, it follows that the photopolymerization process was a first order reaction. The photopolymerization reaction could be identified as a kind of free radical polymerization, while CH₃CH₂O was the active group in the photopolymerization. Besides, AgCl nano-cubic particles were stable under UV irradiation.

Ultrathin tetrahedral amorphous carbon (ta-C) films were deposited by a home developed filtered cathodic vacuum arc technology. The effect of arc current on the structure and property of the prepared films was investigated. Results show that as the arc current increased from 40 A to 70 A, the deposition rate increased, the sp³ fraction increased first and then decreased; when the arc current was 60 A the maximal density of 3.067 g/cm³ and sp³ fraction of 66% was obtained. The variation of residual compressive stress was similar to sp³ fraction. The minimum residual stress was found about 4 GPa for the arc current 40 A. The surface roughness as a function of arc current decreased gradually first and then increased, and when the arc current was 50 A the minimum surface roughness was 0.195 nm. The deposited ions could fill in the defects of substrate which leads to reducing the surface roughness of ultrathin ta-C films.