共查询到20条相似文献,搜索用时 93 毫秒
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强激光辐照红外热像系统时,可造成系统的干扰和破坏,激光的波长不同,对系统的破坏效果也不同.为了保护红外系统窗口以及提高窗口的透过率,红外窗口广泛沉淀类金刚石(DLC)薄膜.当入射的激光波长位于红外系统响应波段外时,激光对系统的破坏首先是激光对DLC薄膜的破坏.以波长为1.06μm的激光为例,研究了脉冲激光对DLC薄膜的损伤机理,建立了DLC薄膜的热冲击效应模型,并通过求解热传导和应力平衡方程,得出了薄膜的温度场和应力场分布.理论分析表明,热应力破坏在脉冲强激光对DLC膜的损伤机理中占主导地位.当 辐照能量密度为E0=100mJ·cm-2时,在薄膜表面距光斑中心约 40μm区域内的压应 力明显超出其断裂强度,将造成膜层的剥离、脱落.理论分析与实验结果基本相符,表明建 立热冲击效应模型的正确性.
关键词:
激光辐照
类金刚石(DLC)薄膜
热冲击效应 相似文献
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用热液金刚石压腔装置结合拉曼光谱技术研究了高温高压下方解石的相变过程及拉曼光谱特征。结果表明:常温条件下,体系压力增至1 666和2 127 MPa时,方解石的拉曼特征峰155cm-1消失,1 087cm-1峰分裂为1 083和1 090cm-1两个谱峰、282cm-1峰突然降至231cm-1,证明其转变为方解石-Ⅱ和方解石-Ⅲ。在起始压力为2 761MPa和低于171℃的升温过程中,方解石-Ⅲ的拉曼散射的各个特征振动峰没有变化。当温度达到171℃,方解石晶体完全变成不透明状,其对称伸缩振动峰1 087cm-1、面内弯曲振动峰713cm-1和晶格振动峰155和282cm-1均发生突变,说明方解石-Ⅲ相变生成一种碳酸钙新相。体系降至常温,该新相一直保持稳定不变,表明高温高压下方解石向碳酸钙新相的转变过程是不可逆的。方解石-Ⅲ与碳酸钙新相之间的相变线方程为P(MPa)=9.09.T(℃)+1 880。碳酸钙新相的对称伸缩振动峰(ν1 087)随压力、温度的变化率分别为dν/dP=5.1(cm-1.GPa-1),dν/dT=-0.055 3(cm-1.℃-1)。 相似文献
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Jingchao Wang Jianwu Yu Liang Huang Hong Luo Xiaopan Liu Zhentao Shang 《固体物理学:研究快报》2024,18(3):2300385
The modulation mechanism of iron (Fe) and manganese (Mn) in transition-metal elements on the interface bonding and mechanical properties of bronze (Cu3Sn)-based/diamond composites is investigated through first-principles calculations. Transition-elements-doping scenarios are investigated employing six-layer slab models. It is revealed that the doping of Fe or Mn can make the Cu3Sn/diamond interface more stable, which effectively improves the wettability of the Cu3Sn/diamond interface based on the calculation results and analysis of interface energy, differential charge density model, and density of states. However, co-doping with both Fe and Mn weakens the wettability of the Cu3Sn/diamond interface. Finally, wettability tests and microstructure characterizations demonstrate that the doping of Fe and Mn represents an effective approach to controlling the interface bonding performance of bronze/diamond composites. 相似文献
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用分子动力学方法模拟计算了在冲击波加载条件下,单晶铁中的结构相变(由体心立方结构α相到六角密排结构ε相),相互作用势采用铁的嵌入式原子势(EAM),单晶铁样品的尺寸为28.7 nm×22.9 nm×22.9 nm,总原子数为1.28×106个。通过推动一个运动活塞对静止靶的作用来产生冲击压缩,加载方向沿单晶铁的[100]晶向。通过对原子位置的追踪,揭示了铁的冲击相变机制,计算结果表明相变机制包括两步:首先是在{011}面上的原子受到沿〈100〉晶向的压缩,使{011}面转化成正六角形密排面;然后是在{011}面上原子沿〈0-11〉晶向的滑移,完成由bcc结构到hcp结构的相变。同时发现滑移面只出现在与冲击波加载方向平行的(011)和(0-11)面上。 相似文献
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本文利用多尺度方法研究了包含孔洞金属材料在冲击加载条件下的动力学行为. 该多尺度方法结合了分子动力学和有限元方法,分子动力学方法运用于局部缺陷区域,而有限元方法运用于整个模型区域,两种方法之间使用桥尺度函数进行连接. 计算结果既包括了系统宏观的物理信息,如应变场、应力场、温度场等,也得到了微观原子的物理信息,如原子能量和位置坐标等. 结合以上的模拟结果,发现孔洞的坍塌与材料屈服强度和冲击强度有关,而孔洞坍塌和坍塌过程中对微喷射原子的压缩过程是形成局部热点的主要原因. 同时也发现孔洞坍塌形成的位错和局部热点可以导致局部绝热剪切带更容易形成.
关键词:
微孔洞
热点
冲击加载
多尺度方法 相似文献
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The effect of pressure on the Raman modes in TeO2 (paratellurite) has been investigated to 30GPa, using the diamond cell and argon as pressure medium. The pressure dependence
of the Raman modes indicates four pressure-induced phase transitions near 1 GPa, 4.5 GPa, 11 GPa and 22 GPa. Of these the
first is the well studied second-order transition fromD
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symmetry toD
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symmetry, driven by a soft acoustic shear mode instability. The remarkable similarity in the Raman spectra of phases I to
IV suggest that only subtle changes in the structure are involved in these phase transitions. The totally different Raman
spectral features of phase V indicate major structural changes at the 22GPa transition. It is suggested that this high pressure-phase
is similar to PbCl2-type, from high pressure crystal chemical considerations. The need for a high pressure X-ray diffraction study on TeO2 is emphasized, to unravel the structure of the various high pressure phases in the system. 相似文献
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通过X射线应力测试和有限元分析相结合的方法,研究了金刚石层厚度对聚晶金刚石复合片(PDC)残余应力的影响,并根据实验测试结果推导出了PDC表面中心与边缘的应力随金刚石层厚度变化的关系式。随着金刚石层厚度由0.5 mm增加到2.0 mm,PDC表面中心的压应力从1 800 MPa下降至700 MPa左右,而边缘部分的应力逐渐由压应力转为拉应力。金刚石层加厚虽然对边缘部分的最大拉应力影响不大,但使PDC边缘拉应力区宽度由0.76 mm增加到了2.85 mm。金刚石层厚度的增加还使得PDC边缘界面附近y方向的最大拉应力和位于界面边缘处的最大剪应力显著加大,这是金刚石层较厚的PDC界面容易产生裂纹的主要原因。 相似文献
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Abstract The application of high pressures to biomaterials can often result in significant structural modifications and, in some cases, also lead to changes in the rates and the equilibria of any associated biological activities. Pressure-induced changes can conveniently be monitored by molecular spectroscopy. We present here a brief overview of the effects of high pressures on the IR and Raman spectra of biomaterials that have been reported over the past 25 years. Examples of the biomaterials that have been examined are model antithyroid drugs, proteins, amino acids, dental materials, human bones, and bioorganometallic compounds. In addition, some recent investigations on the effect of pressure on microbial activity and the conversion of biomass into molecular hydrogen under supercritical water conditions are discussed. Two typical diamond-anvil cells (DACs), which are used for high-pressure vibrational spectroscopic measurements, are also described here. 相似文献
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通过对冲击波点火内爆过程的数值模拟分析点火热斑压缩及形成机制。分析了传统中心点火的内爆过程,热斑主要经历冲击波压缩和惯性压缩过程,点火主要通过惯性压缩来实现。并仔细分析了冲击波点火的内爆压缩过程,从内爆角度来看冲击波点火并不是压缩和点火分开的两步过程,点火冲击波实际参与压缩过程,点火冲击波对热斑的直接影响很有限,热斑仍然主要通过壳层的惯性压缩实现点火。利用惯性压缩的定标关系及冲击波碰撞对壳层影响规律分析了热斑增压的物理机制,冲击波点火是通过点火冲击波与回冲击波的碰撞来提高壳层的密度,从而实现热斑压力的提升。 相似文献