(1. 中國科學(xué)院過程工程研究所 多相復(fù)雜系統(tǒng)國家重點(diǎn)實(shí)驗(yàn)室，北京 100190；
2. 中國環(huán)境監(jiān)測總站，北京 100012)
摘 要: 采用濕式加壓氫還原技術(shù)研究不同包覆階段、不同氫氣分壓對球形石墨顆粒表面金屬鎳鍍層鍍覆均勻性的影響，探討制備具有致密光滑鍍層的Ni/C顆粒的條件及形成機(jī)理。結(jié)果表明：當(dāng)氣體總壓為4 MPa，其中氫氣分壓為65%時(shí)，得到的Ni/C顆粒具有比較致密均勻的鍍覆狀態(tài)；鎳鍍層的最終形貌由鎳晶體形核和生長的動力學(xué)過程決定；非均相形核過程有利于形成均勻鍍層，均相形核和晶體生長都會使鍍層的均勻性降低；通過調(diào)節(jié)反應(yīng)速率，可以控制金屬鎳的結(jié)晶過程，實(shí)現(xiàn)均勻鍍覆。
關(guān)鍵字: 鎳/石墨；結(jié)晶；形核；鍍層均勻性
coating uniformity of Ni/C composite particles
（1. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering,
Chinese Academy of Sciences, Beijing 100190, China;
2. Environmental Monitoring of China, Beijing 100012, China）
Abstract:The effects of different coating stages and partial pressures of hydrogen on the coating uniformity of spherical Ni/C composite particles were studied by pressurized hydrogen reduction. The preparation condition and formation mechanism of Ni/C particles with compact and smooth coatings were investigated. The results show that the ideal coating effect is achieved when the initial pressure of hydrogen occupied 65% of 4MPa initial total pressure. Final coating morphology of Ni/C particles is decided by dynamics of nucleation and growth processes of nickel crystal. Heterogeneous nucleation process is favorable for producing uniform coating, while the homogeneous nucleation and crystal growth processes make the coating uniformity worse.
Key words: nickel/graphite; crystallinity; nucleation; coating uniformity
