Advanced Materials Research Vols. 634-638

Abstract: According to the production process of 45#steel(120t BOF→ slag refining →CC), some system analysis are introduced to research on the type, composition and quantity of large inclusions in casting slab under slag washing process, the effect of slag washing production process on the cleanliness of casting slab is evaluated. The results of the study show that: Under slag washing process, many of large inclusions are spherical inclusions，the main type of large inclusions is CaO-SiO2-Al2O3-MnO complex inclusion andSiO2-Al2O3 inclusion; the content of large inclusions in normal slab is 5.17mg/10kg, it is lower than that under un-slag washing process; the content of large inclusions in head slab is 108.82mg/10kg, it’s 21.05 times higher than that in normal slab; the content of large inclusions in compound casting slab is 15.94mg/10kg, it’s 3.08 times higher than that in normal slab; the content of large inclusions in casting slab is slightly higher under the condition of unsteady casting; the main inclusions with a size of between 140μm and 300μm in head slab, take up 70.13%, the inclusions with a size of more than 300μm is second, take up 29.24%, and the least is inclusions with a size of between 80μm and 140μm, only take up 0.63%. The level of the molten steel fluctuated remarkably, slag entrapment and secondary oxidation is serious at the casting start and compound casting, which cause the cleanliness of casting slab decreasing. Unsteady casting has great effect on the cleanliness of casting slab.

Abstract: According to the production process of 20g steel(120t BOF→ LF→ CC), some system analysis are introduced to research on the content of T[O] and [N] and the type, source, composition and quantity of micro inclusions in refining process, pouring process and casting billet. The results of the study show: the content of T[O] is 93.2ppm in the normal billet which is 37.8ppm more than that at steady state in the export of tundish. The content of T[O] is 140.5ppm in the compound casting billet which is 70.133ppm more than that at non-steady state in the export of tundish. The secondary oxidation of mould is serious at casting progress. In billet, the quality of CaS-SiO2-Al2O3 complex inclusion is the most, the quality of MnS inclusion is the second, and the quality of Al2O3 inclusion is the least. The sulphur content in micro-inclusion of billet is higher. The sulphur content in CaS-SiO2-Al2O3 complex inclusion is 3~15%, the sulphur content in MnS inclusion is 25%. The particle size of less than 10μm in micro-inclusions is the largest. The particle size of 0~5μm is about 60%, the particle size of 5~10μm is about 35%, the particle size of 10~15μm is about 5%. The average total volume rate of micro-inclusion is 0.149% in normal billet. The average total volume rate of micro-inclusion is 0.184% in compound casting billet which is 1.23 times than normal billet. The number of micro-inclusion is 36.5/ mm2 in normal billet. The number of micro-inclusion is 58.5/ mm2 in compound casting billet which is 60.27% higher than normal billet. The non-steady state casting has serious influence on billet cleanliness.

Abstract: According to the production process of grade 45 steel(120tBOF→slag refining→ CC), some system analysis are introduced to research on the type composition and quantity of micro-inclusions, and the effect of slag washing production process on the cleanliness of casting slab is evaluated. The results of the study show that: The content of T[O] is 48.75ppm in normal slab, The content of T[O] is 56.2ppm in head slab, The content of T[O] is 49.2ppm in compound casting slab.The main types of micro-inclusion in slab are MnS inclusion and Al2O3 inclusion. The quality of micro-inclusions is 14.32/mm2 in the normal slab, the quality of micro-inclusions is 17.68 /mm2 in the head slab, the quality of micro-inclusions is 27.94 /mm2 in the compound casting. In the normal slab, the average total volume ratio of micro-inclusions is 0.0458%. The particle size of micro-inclusions is smaller. The particle size of less than 10μm in micro-inclusions is the largest and is about 80%.

Abstract: According to the production process of 20g steel(120t BOF→ LF→ CC), some system analysis are introduced to research on the content of T[O] and [N] and the type, source, composition and quantity of micro inclusions in refining process, pouring process and casting billet. The results of the study show: in billet, the main type of large inclusions is CaO-SiO2-Al2O3-MgO complex inclusion of sulfur contained. The content of large inclusions is 14.5mg/10kg in normal billet. The content of large inclusions is 33.14mg/10kg in compound casting billet which is 1.29 time than normal billet.The content of large inclusions whose particle size is more than 300μm in billet is 8.39mg/10kg, and make up 87% of the total. The content of large inclusions whose particle size is 140-300μm in billet is 2.29mg/10kg, and make up 15.79% of the total. The content of large inclusions whose particle size is 80-140μm in billet is 3.82mg/10kg, and make up 26.35% of the total. Unsteady casting plays an important role in the steel cleanliness.

Abstract: A series of metal molybdates were synthesized as flame-retardants and smoke suppressants for flexible poly (vinyl chloride). The powder of molybdates was characterized by the x-ray diffraction. The flame retardancy, smoke suppression and thermal behavior of PVC treated with a series of molybdates were studied by means of limiting oxygen index (LOI), smoke density rating (SDR), thermogravimetry (TG), differential thermogravimetry (DTG), differential thermal analysis (DTA) and scanning electron microscopy (SEM). The results shown that, the flame retardancy and smoke suppression performance of PVC samples depend on the strength of the Lewis acid which generated in the first degradation stage and the stability of residue char in the second stage. While the strong Lewis acid can also function as cracking catalysts in the second stage, and cracking of the principally hydrocarbon char can promote the generation of volatile organic compounds, which act as efficient fuels. This situation results in less smoke, but increased flame.

Abstract: The paper provides an overview of surface modification and application of fly ash cenospheres. The state of the art research and development of electromagnetic wave absorption materials based on surface treated fly ash cenospheres are summarized.

Abstract: In the context of laminated composite design, the integrated stiffness of the laminate depends on the number of plies, the material and the orientation of the material in each ply. The main issue of design is the prohibitive numerical simulation cost, the early technique (DMO, discrete material optimization; BCP, Bi-value Coding Parameterization Method) consists in transforming the continuous orientation angle variables to discrete design variables as multiphase material selection problems. In this work, a set of continuous orientation angle is directly considered. More precisely, the design task is the orientation of the orthotropic material in each element of the discretization and the ratio of ply thickness. In order to reduce the computational effort, Proper Orthogonal Decomposition (POD) applied to decrease the number of design variables. The numerical results in a simple case show that the proposed method is available.

Abstract: The effects of the functionalized multi-walled carbon nanotubes (MWCNT-P) on the curing behavior of a diglycidyl ether of bisphenol-A epoxy (DGEBA) in the presence of 4,4'-methylenedianiline were investigated by non-isothermal differential scanning calorimetry. Activation energy (E_a) was obtained through Kissinger and Ozawa methodsItalic text respectively, and reaction order(n) was educed by Crane equation. The results showed that the addition of MWCNT-P enhanced the cure reaction of DGEBA with 4,4'-methylenedianiline, compared with pure epoxy system, epoxy containing MWCNT-P exhibited a lower activation energy. Both systems presented the same reaction orders, which indicated MWCNT-P did not change the auto-catalytic cure reaction mechanism of the epoxy resin.

Abstract: In this paper, the nano-β-SiC/Al2O3 composite absorbing coatings produced by plasma spraying technology were reported. Where, β-SiC phase dissipates in the boundary of Al2O3 grains. Then, the relationship between microstructure and dielectric properties was built. Some results are shown as follows: with increasing of flatten ratio of particle and pores, the microwave reflectivity coefficient of composite absorbing coatings decreases and ranges to low frequency. And, there exists a threshold value, about 30wt% of nano β-SiC, the microwave reflectivity coefficient of composite absorbing coatings can reach to -8 dB. The infrared properties of β-SiC/ Al2O3composite absorbing coatings with experiment is about 0.6~0.8, respectively.

Abstract: Influence of the composition of cast penetration agents on the microstructure of Tungsten-Chromium surface composite layer was researched by conventional cast penetration process with main cast penetration agents of WC and high carbon ferro-chrome. The result is shown that a certain thickness composite layer metallurgical bonding with matrix is formed on the surface of ZG230-450 cast under the condition of experiment. The relative quantity of chrome carbide and tungsten carbide in surface composite layer changes with the increase of WC and the shape of tungsten carbide changes from discontinuous reticulation into sunflower and then into banding shape with the increase of WC and high carbon ferro-chrome.