Study On Preparation And Properties Of Negative Thermal Expansion Materials Mn3(Cu_0.6Si_0.15Ge_0.25)N

Materials expand with heat will bring negative impact when they are used in extreme conditions. The discovery and application of negative thermal expansion (NTE) materials provide an important way to solve thermal expansion mismatch of material in engineering application. Due to the special requirements for thermal expansion properties in cryogenic engineering, we explored some NTE materials with excellent NTE properties during cryogenic temperature area in this study. Some materials with controllable thermal expansion coefficient were prepared with doping method based NTE materials.Antiperovskite manganese nitride Mn3(Cu0.6Si0.15Ge0.25)N were prepared by mechanical alloying and followed by solid state sintering at800℃,830℃,860℃,890℃,920℃,950℃, and the thermal expansion behavior of Mn3(Cu0.6Si0.15Ge0.25)N with different sintering temperature were investigated. On the basis of antiperovskite manganese nitride Mn3(Cu0.6Si0.15Ge0.25)N material, Mn3(Cu0.6Si0.15Ge0.25)N/Ag and (Mn1-xCox)3(Cu0.6Si0.15Ge0.25)N NTE materials were synthesized by mechanical ball milling and solid state sintering method; Mn3(Cu0.6Si0.15Ge0.25)N/Sn were synthesized by Spark Plasma Sintering method.(1) The thermal expansion behavior of Mn3(Cu0.6Si0.15Ge0.25)N can be tailored by adjusting the sintering temperature. This manganese nitride material may possibly be exploited to design the critical component in cryogenic engineering and aerospace areas;(2) The NTE operation-temperature window of Mn3(Cu0.6Si0.15Ge0.25)N/Ag shifts toward room temperature region with increasing Ag content, the electrical conductivity and thermal conductivity of this composites have no relationship with the negative thermal expansion properties;(3) The NTE operation-temperature window of Mn3(Cu0.6Si0.15Ge0.25)N/Sn shifts toward higher temperature region with increasing Sn content, and it does not affect the width of the NTE operation-temperature window and the coefficient of negative thermal expansion;(4) The change value of linear thermal expansions in the NTE operation-temperature window decreases with increasing Co content. The study found that these materials have good NTE properties in certain temperature region, furthermore, the materials with controllable coefficient of thermal expansion can acquired by doping or tailoring the content of component.