Thermodynamic modeling of ZrO_(2)−CaO−TiO_(2)system

The phase diagram of ZrO_(2)−CaO−TiO_(2)system was essential for the development of photocatalytic materials and refractory materials.In this work,the ZrO_(2)−CaO−TiO_(2)system was accessed by using the CALPHAD method.The substitutional solution models were used to describe liquid and solid solution phases,the sub-lattice models were used to describe ternary compounds,and then the thermodynamic parameters were obtained by the least square method combined with literature experiment results.The acquired thermodynamic parameters were used to calculate the isothermal sections of the ZrO_(2)−CaO−TiO_(2)system at 1473 and 1673 K.There existed a good agreement between experimental and predicted phase relationships,the experimental points which were inconsistent with calculated results may be attributed to experimental errors and the sluggish kinetics of cations for ZrO_(2)-based materials.In order to further verify the validity of the database,the thermodynamic parameters were also used to simulate the thermodynamic properties(specific heat capacity,enthalpy,and entropy)of CaZrTi_(2)O_(7) within 5%errors.Good consistency demonstrated that the present thermodynamic database was self-consistent and credible.

Inhibition effects of dexamethasone on matrix metalloproteinase in osteoarthritis cells

Objective:To investigate the inhibition effect of dexamethasone with different concentration gradients on the expression of MMP-1,-3,and-13 in a bone joint cell model of IL-1β-induced SW1353 cells.Methods:The SW1353 cells were placed in a culture medium containing 10^(1)-10^(8) nmol/L dexamethasone,and after 12 hours of culture,the appropriate intervention concentration range of dexamethasone was screened by the MTS for subsequent experiments.After SW1353 cells were induced with 10 ng/mL IL-1β,10^(1)-10^(7) nmol/L dexamethasone was given for intervention,and RT-PCR was used to detect the mRNA expression of MMP-1,-3,and-13.The protein was extracted after the intervention of 104 nmol/L dexamethasone,and western blot was used to detect the protein expression of MMP-1,-3,and-13.Results:MTS proliferation experiment results showed that 10^(1)-10^(7) nmol/L dexamethasone had no significant effect on SW1353 cell viability,while 10^(8) nmol/L dexamethasone had a significant inhibitory effect on SW1353(p<0.05).There was no obvious effect on cell viability after adding 10 ng/mL IL-1β.RT-PCR results indicated that the IL-1βgroup had a significant increase in the mRNA expression of MMP-1,-3,and-13 compared with the blank control group,and the difference was statistically significant(p<0.05).After intervention with 102-10^(7) nmol/L dexamethasone,MMP-1 mRNA expression decreased(p<0.05);after intervention with 103-10^(7) nmol/L dexamethasone,MMP-3 mRNA expression decreased(p<0.05);after intervention with 10-10^(7) nmol/L dexamethasone,the mRNA expression of MMP-13 decreased(p<0.05).The Western blot results showed that compared with the blank control group,the protein levels of MMP-1,-3,and-13 in the IL-1βgroup were significantly increased;the protein levels of MMP-1,-3,and-13 were significantly reduced after the intervention of 104 nmol/L dexamethasone.Conclusion:Dexamethasone can inhibit the expression of MMP1,MMP-3,and MMP-13 in the IL-1β-induced OA cell model at the mRNA and protein levels.

Interaction mechanism between BaZrO_(3)/Y_(2)O_(3) refractory and Ti_(2)Ni alloy melts

The titanium alloys with highly chemical activity require stable crucible refractories that can withstand the erosion of alloy melts.The phase composition and microstructure are crucial factors that affect the stability of the refractory crucible.The effect of Y_(2)O_(3) on the composition and microstructure of BaZrO_(3) crucible was systematically investigated,and the improved mechanism of the stability of BaZrO_(3)/Y_(2)O_(3) crucible was clarified in comparison with the BaZrO_(3) crucible.The results showed that the erosion layer thickness of the BaZrO_(3)/Y_(2)O_(3) crucible was only 63μm,which was far less than that in the BaZrO_(3) crucible(485μm),and the erosion layer in the BaZrO_(3)/Y_(2)O_(3) crucible also exhibited a higher density than that in the BaZrO_(3) crucible.During the sintering,Y_(2)O_(3) could improve the densification of the BaZrO_(3) crucible due to the solid solution effect between Y_(2)O_(3) and ZrO_(2),which also caused the evaporation of BaO,resulting in the generation of a Y_(2)O_(3)(ZrO_(2))film on the surface of the crucible.Furthermore,the Y_(2)O_(3)(ZrO_(2))had higher thermodynamic stability than Y_(2)O_(3),confirming that the BaZrO_(3)/Y_(2)O_(3) crucible with high density exhibited a superior erosion resistance to titanium alloys.This dual-phase structure provides a strategy to design a long-life and stable refractory for melting titanium alloys.

Effect of controlled rolling/controlled cooling parameters on microstructure and mechanical properties of the novel pipeline steel

The study of controlled rolling/controlled cooling process parameters which affect the microstructure and mechanical properties of a novel pipeline steel has been optimized by the orthogonal experiment with four factors and three levels in this paper. However, the parameters of thermo-mechanical control process （TMCP） optimized by the Gleeble-3500 hot simulator could not satisfy performance requirements of the X100 pipeline steel. In order to improve the performance of this steel, the influence of finish cooling temperature （FCT） on the microstructure and property is studied in detail. It is found that, as this steel is thermo-mechanically treated by this set of parameters （the start heating temperature, finish rolling temperature （FRT）, FCT and cooling rate of 1,180 ℃, 810 ℃, 350 ℃ and 35 ℃/s, respectively）, the micro- structures are mainly composed of granular bainite （GB） and acicular ferrite （AF）. The effective grain sizes are below 20 μm; the steel reaches the optimal balance between the strength and the toughness; the yield strength is 695 MPa; the tensile strength is 768 MPa; the elongation is 16.6 %; the impact energy is 262 J at room temperature. All indexes could meet the requirements of X100 pipeline steel.