Formation Mechanism of Al2O3-YAG Amorphous Ceramic Coating Deposited via Atmospheric Plasma Spraying

This study mainly investigated the formation mechanism of Al2O3-YAG(Al5Y3O12) amorphous coating prepared by atmospheric plasma spraying. Nano and micro-sized powders with low eutectic point ratio were selected as raw materials for comparison. XRD, SEM and EBSD were used to analyze the phase composition, morphologies, phase distribution and structure of the coating. The crystal structures of the possible existed phases were studied to analyze the crystallization chemistry of powder droplets. It is concluded that the composition ratio of powders and particle size should be also considered as the key factors for the preparation of amorphous coatings besides the high enthalpy and ultra-fast cooling rate of thermal spray technology. The as-sprayable powder chose multiple components with low eutectic point ratio distributed uniformly at nano-scale or sub-micro scale, and can reacted to form the new phase crystal with high coordination numbers of cations.

METHOD ACHIEVING COOLING UNIFORMITY AND OPTIMAL PLATE-CURVATURE DURING ULTRA-FAST COOLING IN A HSM

The flow field in the top and bottom surface of the hot rolled strip is different during cooling process with effect of gravity. Then it can affect the strip cooling uniformity of the top and bottom surface, and the plate curvature problems may be appeared. The finite element method was taken to study the plate curvature affecting law and a conclusion was obtained: the uniformity of the heat transfer coefficient in the top and bottom surface was the key to keep plate curvature well after rolling. The finite volume method was taken to calculate the heat transfer coefficient during run-out table laminar cooling (LC) and ultra-fast cooling (UFC) with different top nozzle fluxes and water flux ratios. The heat transfer coefficient and its distribution with different cooling methods and process parameters were obtained, and some conclusions were obtained by analysis: the bottom and top surface heat transfer coefficient can be kept nearly the same by adjusting water flux ratio between the bottom nozzle and top nozzle. The optimal water flux ratios of laminar cooling were 1.20 and 1.15 when top nozzle fluxes were 100m3/h and 120m3/h respectively. The optimal water flux ratios of ultra fast cooling were 1.08, 1.10, 1.15, 1.20 and 1.20 when top nozzle fluxes were 80m3/h, 100m3/h, 120m3/h, 140m3/h and 160m3/h respectively. The obtained results and water flux ratio calculating model were used in several strip cooling lines of the hot strip mill lines and obtained favorable effect.

Abstract 19: Ultra-Fast Cooling Induced by Total Liquid Ventilation Provides Neuroprotection Through a Delay in the Acute Systemic Inflammatory Response After Cardiac Arrest in Rabbits

Introduction: Ultra-fast cooling with total liquid ventilation (TLV) is potently protective in animal models of cardiac arrest. Hypothesis: Here, we hypothesized that this protection involves a mitigation of the acute phase of the inflammatory syndrome after cardiac arrest. Methods: Rabbits were anesthetized and submitted to 10 min of ventricular fibrillation. After resuscitation, animals underwent normothermic follow-up (Control, n=6) or ultra-fast cooling by TLV started after resuscitation (TLV, n=6). TLV was used for induction of cooling during 20 min and hypothermia was further maintained during 3 h using external techniques before rewarming. A third group was submitted to a Sham procedure (n=5). Survival and neurological dysfunction were assessed during 3 days. Results: TLV improved the clinical neurological recovery as compared to Control group after cardiac arrest. It was corroborated by histological examination showing an attenuation of neuronal degeneration in parasagittal cortex and hippocampus in TLV vs Control groups. After resuscitation, TLV delayed the elevation of interleukin-6 blood levels as compared to Control after cardiac arrest (e.g., 298±63 vs 991±471 pg/ml at 180 min after cardiac arrest in TLV vs Control, respectively). Blood cytometry analyses showed a massive recruitment of neutrophils and leukocytes (including T4, T8 and B-lymphocytes) in both groups. The early lymphocytosis was attenuated in TLV vs Control groups, despite not achieving statistical significance. Blood levels of high-mobility group box 1 increased rapidly and similarly in both groups after cardiac arrest. This suggests that TLV does not mitigate the early release of danger-associated molecular patterns after resuscitation, which is closely related to the immediate cell death after resuscitation. Altogether, these results show an attenuation of the early inflammatory response during hypothermia, suggesting a role of early but not delayed inflammation in the mechanism of ultra-fast cooling after cardiac arrest. Conclusion: Beneficial effect of hypothermic TLV could be explained by a delay in immune peripheral cells activation and cytokine release, rather than sustained inhibition of inflammation after cardiac arrest.