Wet dust removal systems used to control dust in the polishing or grinding process of Mg alloy products are frequently associated with potential hydrogen explosion caused by magnesium-water reaction.For purpose of avo...Wet dust removal systems used to control dust in the polishing or grinding process of Mg alloy products are frequently associated with potential hydrogen explosion caused by magnesium-water reaction.For purpose of avoiding hydrogen explosion risks,we try to use a combination of chitosan(CS)and sodium phosphate(SP)to inhibit the hydrogen evolution reaction between magnesium alloy waste dust and water.The hydrogen evolution curves and chemical kinetics modeling for ten different mixing ratios demonstrate that 0.4wt%CS+0.1wt%SP yields the best inhibition efficiency with hydrogen generation rate of almost zero.SEM and EDS analyses indicate that this composite inhibitor can create a uniform,smooth,tight protective film over the surface of the alloy dust particles.FTIR and XRD analysis of the chemical composition of the surface film show that this protective film contains CS and SP chemically adsorbed on the surface of ZK60 but no detectable Mg(OH)_(2),suggesting that magnesium-water reaction was totally blocked.Our new method offers a thorough solution to hydrogen explosion by inhibiting the hydrogen generation of magnesium alloy waste dust in a wet dust removal system.展开更多
Metal dusting attacks iron,low and high alloy steels and nickel-or cobalt-base alloys by disintegrating bulk metals and alloys into metal particles in a coke deposit.It occurs in strongly carburising gas atmospheres(c...Metal dusting attacks iron,low and high alloy steels and nickel-or cobalt-base alloys by disintegrating bulk metals and alloys into metal particles in a coke deposit.It occurs in strongly carburising gas atmospheres(carbon activity a_C>1) at elevated temperatures(400℃～1000℃).This phenomenon has been studied for decades,but the detailed mechanism is still not well understood.Current methods of protection against metal dusting are either directed to the process conditions-temperature and gas composition-or to the development of a dense adherent oxide layer on the surface of the alloy by selective oxidation.However,metal dusting still occurs by carbon dissolving in the base metal via defects in the oxide scale.The research work at UNSW is aimed at determining the detailed mechanism of metal dusting of both ferritic and austenitic alloys,in particular the microprocesses of graphite deposition,nanoparticle formation and underlying metal destruction.This work was carried out using surface observation,crosssection analysis by focused ion beam and electron microscopic examination of coke deposits at different stages of the reaction.It was found that surface orientation affected carbon deposition and metal dusting at the initial stage of the reaction.Metal dusting occurred only when graphite grew into the metal interior where the volume expansion is responsible for metal disintegration and dusting.It was also found that the metal dusting process could be significantly changed by alterations in alloy chemistry.Germanium was found to affect the iron dusting process by destabilising Fe_3C but increasing the rate of carbon deposition and dusting,which questions the role of cementite in ferritic alloy dusting.Whilst adding copper to iron did not change the carburisation kinetics,cementite formation and coke morphology,copper alloying reduced nickel and nickel-base alloy dusting rates significantly.Application of these fundamental results to the dusting behaviour of engineering alloys is discussed.展开更多
为推进镁铝合金加工企业粉尘爆炸风险分级管控体系建设,有效预防粉尘爆炸事故发生,提出抛光镁铝合金粉尘爆炸风险评估模型。首先,从粉尘爆炸特性参数角度评估抛光镁铝合金粉尘爆炸危险性等级;然后,从人、机、管、环四方面建立镁铝合金...为推进镁铝合金加工企业粉尘爆炸风险分级管控体系建设,有效预防粉尘爆炸事故发生,提出抛光镁铝合金粉尘爆炸风险评估模型。首先,从粉尘爆炸特性参数角度评估抛光镁铝合金粉尘爆炸危险性等级;然后,从人、机、管、环四方面建立镁铝合金抛光作业场所爆炸风险评估指标体系,采用层次分析法(Analytic Hierarchy Process,AHP)和指标相关性权重确定法(Criteria Importance Though Intercriteria Correlation,CRITIC)进行组合赋权,确定各二级指标权重,建立优劣解距离法(Technique for Order Preference by Similarity to Ideal Solution,TOPSIS)评估模型,得出作业场所爆炸风险等级;最后,运用风险矩阵评估其综合风险。使用上述模型评估某企业抛光车间的粉尘爆炸风险,结果表明:抛光镁铝合金粉尘爆炸危险性为Ⅲ级,危险性较大;作业场所爆炸风险等级为Ⅲ级;故而得到抛光镁铝合金粉尘爆炸风险等级为C级,属于中度风险。爆炸危险性等级依据粉尘爆炸特性试验结果判定,作业场所爆炸风险评估结果与粉尘爆炸领域专家评估结果一致,证明该粉尘爆炸风险评估体系和评估模型具有准确性。展开更多
基金This work was supported by the National Natural Science Foundation of China(52074066).
文摘Wet dust removal systems used to control dust in the polishing or grinding process of Mg alloy products are frequently associated with potential hydrogen explosion caused by magnesium-water reaction.For purpose of avoiding hydrogen explosion risks,we try to use a combination of chitosan(CS)and sodium phosphate(SP)to inhibit the hydrogen evolution reaction between magnesium alloy waste dust and water.The hydrogen evolution curves and chemical kinetics modeling for ten different mixing ratios demonstrate that 0.4wt%CS+0.1wt%SP yields the best inhibition efficiency with hydrogen generation rate of almost zero.SEM and EDS analyses indicate that this composite inhibitor can create a uniform,smooth,tight protective film over the surface of the alloy dust particles.FTIR and XRD analysis of the chemical composition of the surface film show that this protective film contains CS and SP chemically adsorbed on the surface of ZK60 but no detectable Mg(OH)_(2),suggesting that magnesium-water reaction was totally blocked.Our new method offers a thorough solution to hydrogen explosion by inhibiting the hydrogen generation of magnesium alloy waste dust in a wet dust removal system.
基金Support for this study by the Australian Research Council is gratefully acknowledged.
文摘Metal dusting attacks iron,low and high alloy steels and nickel-or cobalt-base alloys by disintegrating bulk metals and alloys into metal particles in a coke deposit.It occurs in strongly carburising gas atmospheres(carbon activity a_C>1) at elevated temperatures(400℃～1000℃).This phenomenon has been studied for decades,but the detailed mechanism is still not well understood.Current methods of protection against metal dusting are either directed to the process conditions-temperature and gas composition-or to the development of a dense adherent oxide layer on the surface of the alloy by selective oxidation.However,metal dusting still occurs by carbon dissolving in the base metal via defects in the oxide scale.The research work at UNSW is aimed at determining the detailed mechanism of metal dusting of both ferritic and austenitic alloys,in particular the microprocesses of graphite deposition,nanoparticle formation and underlying metal destruction.This work was carried out using surface observation,crosssection analysis by focused ion beam and electron microscopic examination of coke deposits at different stages of the reaction.It was found that surface orientation affected carbon deposition and metal dusting at the initial stage of the reaction.Metal dusting occurred only when graphite grew into the metal interior where the volume expansion is responsible for metal disintegration and dusting.It was also found that the metal dusting process could be significantly changed by alterations in alloy chemistry.Germanium was found to affect the iron dusting process by destabilising Fe_3C but increasing the rate of carbon deposition and dusting,which questions the role of cementite in ferritic alloy dusting.Whilst adding copper to iron did not change the carburisation kinetics,cementite formation and coke morphology,copper alloying reduced nickel and nickel-base alloy dusting rates significantly.Application of these fundamental results to the dusting behaviour of engineering alloys is discussed.
文摘为推进镁铝合金加工企业粉尘爆炸风险分级管控体系建设,有效预防粉尘爆炸事故发生,提出抛光镁铝合金粉尘爆炸风险评估模型。首先,从粉尘爆炸特性参数角度评估抛光镁铝合金粉尘爆炸危险性等级;然后,从人、机、管、环四方面建立镁铝合金抛光作业场所爆炸风险评估指标体系,采用层次分析法(Analytic Hierarchy Process,AHP)和指标相关性权重确定法(Criteria Importance Though Intercriteria Correlation,CRITIC)进行组合赋权,确定各二级指标权重,建立优劣解距离法(Technique for Order Preference by Similarity to Ideal Solution,TOPSIS)评估模型,得出作业场所爆炸风险等级;最后,运用风险矩阵评估其综合风险。使用上述模型评估某企业抛光车间的粉尘爆炸风险,结果表明:抛光镁铝合金粉尘爆炸危险性为Ⅲ级,危险性较大;作业场所爆炸风险等级为Ⅲ级;故而得到抛光镁铝合金粉尘爆炸风险等级为C级,属于中度风险。爆炸危险性等级依据粉尘爆炸特性试验结果判定,作业场所爆炸风险评估结果与粉尘爆炸领域专家评估结果一致,证明该粉尘爆炸风险评估体系和评估模型具有准确性。
