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为解决商用选区激光熔化设备制作散热器生产效率低的问题并使之保持良好的散热特性与机械性能,采用纯Ni粉末进行不同层厚选区激光熔化成形获得了高效制作、性能良好的样品。从致密度、金相显微组织、热特性、机械性能等方面展开研究,一定范围内增加层厚能够提高成形效率并且保证成形样品的热特性与机械性能。超过激光可烧结的层厚阈值时,烧结轨迹为球化线。在可烧结层厚范围内,改变工艺参数能使成形体均接近完全致密。层厚由20μm增加至40μm,初始枝晶间距由305 nm增至639 nm。热导率由20μm时的99.28 W/K·m降低至40μm成形时的92.48 W/K·m。25℃~100℃时,40μm层厚成形体热膨胀系数由11.02×10~(-6)m/(m·℃)升至12.9×10~(-6)m/(m·℃),低于对应温度区间内20μm层厚成形体热膨胀系数由11.42×10~(-6)m/(m·℃)升至13.4×10~(-6)m/(m·℃)。20μm层厚与40μm层厚成形试样的拉伸强度均远高于国标锻压件。应用选区激光熔化技术成形散热器,采用40μm层厚成形的生产效率比20μm层厚成形提高34.6%。
In order to solve the problem of low production efficiency of heat sink produced by commercial laser cutting equipment and keep it good heat dissipation and mechanical properties, pure Ni powder was used for laser melting forming with different layer thicknesses to obtain high efficiency and good performance samples. From density, metallographic microstructure, thermal properties, mechanical properties and other aspects of the study, within a certain range to increase layer thickness can improve the forming efficiency and to ensure the thermal properties of the formed sample and mechanical properties. Beyond the laser sinterable layer thickness threshold, the sintering trajectory is a spheroidized line. In the sinterable layer thickness range, changing the process parameters can make the compact body are nearly completely densified. The layer thickness increased from 20μm to 40μm, and the initial dendrite spacing increased from 305 nm to 639 nm. The thermal conductivity decreased from 99.28 W / K · m at 20 μm to 92.48 W / K · m at 40 μm molding. From 25 ℃ to 100 ℃, the thermal expansion coefficient of the 40μm thick formed body increased from 11.02 × 10 -6 m / (m · ℃) to 12.9 × 10 -6 m / (m · ℃) The coefficient of thermal expansion of the 20 μm thick formed body increased from 11.42 × 10 -6 m / (m · ℃) to 13.4 × 10 -6 m / (m · ℃) in the corresponding temperature range. Tensile strength of 20μm layer thickness and 40μm layer thickness forming samples are much higher than the national standard forging. Application of selective laser melting technology forming heat sink, the use of 40μm layer thickness forming efficiency than the 20μm layer thickness forming increased by 34.6%.