High temperature oxidation performance of an Nb-Ti-stabilized 430 ferritic stainless steel (NTS430FSS) and SUS 430 ferritic stainless steel (SUS430FSS) was comparatively investigated by means of isothermal oxidation test, metallographic observation, scanning electron microscope (SEM) along with chemical microanalysis by energy dispersive spectrometry (EDS) and X-ray diffraction analysis. The results show that the oxidation weight gain was reduced for the steel with Nb and Ti addition. And the oxidation activation energies were 72.6 kJ/mol and 121.6 kJ/mol for the steel without and with Nb and Ti addition respectively. The adhesion between the oxide scale and matrix was enhanced by titanium oxide which dopped into the oxide scale. As a result, the Nb-Ti-stabilized 430 ferritic stainless steel exhibited better high temperature oxidation resistance.

The effect of minor addition of Sr and/or Mn on the microstructure and mechanical properties of the wrought Mg-8Li-3Al alloy were investigated by means of optical microscopy, scanning electron microscopy, X-ray diffraction studies, and tensile tests to reveal the variations in microstructures and mechanical behavior during processing. The results show that the alloy of Mg-8Li-3Al mainly consists of α-Mg, β-Li phases and Al₁₂Mg₁₇ intermetallic compound. Sr and Mn addition results in the precipitation of Al₄Sr and Al₂Mn₃. The microstructure of the alloy is refined with the addition of Sr and Mn, respectively. Moreover, the refining effect of Sr is better than Mn at the same mass fraction addition. The tensile strength of the alloys is improved with the addition of Sr and Mn. The tensile strength, yield stress and elongation of Mg-8Li-3Al-0.5Sr-0.5Mn alloy after extrusion are 242.15 MPa, 206.96 MPa and 22.43%, which are increased by 14.98%, 28.11% and 8.31% respectively in comparison with the those of the bare Mg-8Li-3Al alloy.

Microporosity in a single crystal nickel-based superalloy DD33 solidified by high rate solidification (HRS) and liquid metal cooling (LMC) process was investigated by the X-ray tomography (XRT). It is found that the pressure drop was reduced because of the larger volume fraction of eutectic in the alloy solidified by LMC, which results in less solidification-pore (S-pore) formation. Homogenization-pore (H-pore) forms in interdendritic regions during solution heat treatment, which results in the increase of volume fraction of porosities during heat treatment. However, lower level of H-pore in the LMC samples can be attributed to the finer dendrite arm spacing and the lower segregation.

The effect of secondary orientation on thermal fatigue behavior of a third generation nickel-based single crystal superalloy DD33 was investigated. Samples with different secondary orientations were machined along (100) and (110) plane, respectively, and thermal fatigue test was performed cyclicly between room temperature and 1100^oC. It was found that different initiation sites and propagation orientations of the thermal fatigue cracks were observed in samples with different secondary orientations. In samples with secondary orientation of [100], thermal cracks initiated at the edge of the holes along a direction with 45^o incline to the directional solidification (DS) direction and propagated along also the derection with 45^o incline to the DS direction. While in samples with secondary orientation of [110], thermal cracks initiated at the edge of the holes vertical to the DS direction and propagated along the DS direction. In general, samples with secondary orientation of [100] exhibited better thermal fatigue properties than that of [110] samples.

Two-step intercalation montmorillonites were prepared with montmorillonites (MMTs) as raw material and firstly octadecylamine was used as an modifier to prepare organic MMTs and then 8-hydroxyquinoline as the inhibitor to treat organic MMTs. The MMTs were characterized by infrared spectra and X-ray diffraction. The results show that octadecylamine and 8-hydroxyquinoline have intercalated into the layer of MMTs, and the spacing of MMTs respectively enlarged from 1.17 nm to 1.57 nm and 1.82 nm. The resultant MMTs enhanced significantly the corrosion resistance of the epoxy coating according to EIS results.

Effect of heating process with a designed heating rate on the austenite grain growth behavior of the as-cast 30Cr2Ni4MoV steel was studied, which aims to simulate the actual heating process during production of large-sized forging. The results show that for a fixed holding time the average size of austenitic grains increases exponentially with the increasing heating temperature; for a fixed heating temperature the average size of austenite grains changes approximate parabolically with the increasing holding time; when the heating temperature is increased to 1100℃, the grains grow up sharply; The Beck equation which describes the dependence of the average size of austenite grains on holding time during heating process of the as-cast 30Cr2Ni4MoV steel was acquired and models of the grain growth under the conditions of isothermal and non-isothermal respectively were also established.

Tensile tests of the 9% pre-strained S30408 austenitic stainless steel for cryogenic vessels were conducted at different cryogenic temperatures. Microstructures of the fractured specimens were examined. The results show that the phase transformation from γ-austenite to α'-martensite in the 9% pre-strained S30408 austenitic stainless steel was promoted under tensile deformation with a strain rate of 1.0×10^-3/s at cryogenic temperatures. The lower the temperature at which tensile testing was performed, the more the amount of the phase transformation from γ into α', and the finer the martensite lath. The martensite transformation can be induced by the deformation of austenite, and the interface relationship between the α'-martensite and the γ-austenite phases is {111}γ∥{011}α' and <101>γ∥<111>α', which is in accord with the K-S model.

The present model, which described the nucleation and growth of crystals and diffusion of solute atoms during solidification, is extended by means of cellular automata method to simulate the growth morphology of dendrites and the solute distribution during the solidification process of welding pool of Fe-0.05%C binary alloy. Meanwhile, the phase distribution after solidification was simulated on basis of the Fe-C binary phase diagram and according to the principle that different solute concentration corresponds to different phase. Besides, a mathematical model is acquired to describe the relationship between the ratio of α+P to P+Fe₃C_Ⅱ with the parameters such as the solute concentration, the cooling rate and the basal number of nucleation. The results show that the simulated results of the microstructure distribution of weld mild steel is in good agreement with the experimental ones. Therefore, the microstructure model based on changes of solute concentration can effectively predict the real microstructure of weld joint of mild steel. The impact of solute concentration, cooling rate, and the basal number of nucleation on the ratio of α+P to P+Fe₃C_Ⅱ is much obvious, but the effect of each factor is independent relatively. The deduced regressive equation of microstructure control is highly significant, and it can provide data as reference for microstructure optimization of the weld joint.

Diamond-like carbon films were synthesized on stainless steel and silicon substrates by a linear ion beam combined with sputtering deposition system. Effect of substrate negative bias and the buffer layers on the microstructure and properties of DLC films was investigated. The results showed that,with the same buffer layer, the number of sp³ bond in the films decreased when the bias voltage changed from -100 V to -200 V, but the hardness and the adhesion strength were enhanced because of a better compactness of the films; on the other hand, with the increasing thickness and number of deposited layers, the number of sp³ bond in the films reduced when the bias voltage was -200 V, meanwhile the hardness of the multilayered film and the thickness of the buffer layer decreased together; the number of sp³ bond in the film and hardness of the DLC films prepared at the bias voltage of -100 V were little affected by the thickness of the buffer layer and number of deposited layers; among others a DLC film of 4.92 μm thick prepared on a 1.7 μm thick buffer layer of Cr/CrC showed the best comprehensive properties, of which the hardness is 29.4 GPa and friction coefficient is less than 0.1.

Mg(OH)₂ films were electrodeposited on the surface of AZ91D magnesium alloys in Mg(NO₃)₂ solutions at room temperature using cathodic potentiostatic and potentiostatic-pulse methods respectively. The characteristics of the Mg(OH)₂ films were investigated by scanning electronic microscope (SEM) and X-ray diffraction (XRD). The corrosion resistance of the films was evaluated using potentiodynamic polarization tests. The results show that the Mg(OH)₂ films are uniform and compact without obvious defects. Mg(OH)₂ films enhanced the corrosion resistance of the AZ91D alloy. The Mg(OH)₂ film deposited by potentiostatic pulse method was superior to that deposited by potentiostatic method in terms of uniformity and compactness and corrosion resistance.

Hierarchically mesoporous silicas could be prepared by means of a previously reported partitioned cooperative self-assembly process (PCSA process) using nonionic triblock copolymer surfactant (P123) as template and sodium silicate as silica precursor. It was found that the partitioning conditions play a key role in inducing the formation of hierarchically mesoporous structures. Under suitable partitioning conditions, in terms of the amounts of sodium silicate in two partitioned additions and interval time between them, the PCSA process allows the preparation of hierarchically ordered mesoporous silicas based on cheap sodium silicate via such a simple templating system, without resorting to additives, multiple templates or complicated synthetic conditions. The size of the first series mesopores is around 9 nm, while the second series of large pores possesses broadened pore size distributions ranging from 20 nm to 200 nm. Under certain partitioning conditions (SS6-4h-4.5 and SS3-4h-7.5), hierarchically mesoporous silicas with the first series of ordered mesopores can be prepared.

A new curing agent (PBMI-DDE) for epoxy resin was synthesized from phthalide-containing bismaleimide (PBMI) and aromatic amine (DDE) according to the Michael addition reaction. The chemical structure of PBMI-DDE was characterized by ¹H NMR spectroscopy and Fourier transform infrared spectroscopy (FTIR). The curing performance and kinetics of E-51/ PBMI-DDE was studied by DSC. Apparent activation energy evaluated according to Kissinger model or FWO model is 46.7 or 49.1 kJ/mol, respectively, and the calculated reaction order is 0.88 based on Crane method. The DMA and TGA results show that the cured resin possesses excellent thermostability with a glass transition temperature 153℃ for the completely cured resin.