搜狗做题网化学中的DSC,TG是什么的缩写啊?
来源：学生作业帮 编辑：搜狗做题网作业帮 分类：英语作业 时间：2024/04/27 23:10:21
化学中的DSC,TG是什么的缩写啊?
DSC 差示扫描量热法
差示扫描量热法（differential scanning calorimetry）这项技术被广泛应用于一系列应用,它既是一种例行的质量测试和作为一个研究工具.该设备易于校准,使用熔点低,是一种快速和可靠的热分析方法.差示扫描量热法(DSC)是在程序控制温度下,测量输给物质和参比物的功率差与温度关系的一种技术.DSC和DTA仪器装置相似,所不同的是在试样和参比物容器下装有两组补偿加热丝,当试样在加热过程中由于热效应与参比物之间出现温差ΔT时,通过差热放大电路和差动热量补偿放大器,使流入补偿电热丝的电流发生变化,当试样吸热时,补偿放大器使试样一边的电流立即增大；反之,当试样放热时则使参比物一边的电流增大,直到两边热量平衡,温差ΔT消失为止.换句话说,试样在热反应时发生的热量变化,由于及时输入电功率而得到补偿,所以实际记录的是试样和参比物下面两只电热补偿的热功率之差随时间t的变化关系.如果升温速率恒定,记录的也就是热功率之差随温度T的变化关系. 物质在温度变化过程中,往往伴随着微观结构和宏观物理,化学等性质的变化.宏观上的物理,化学性质的变化通常与物质的组成和微观结构相关联.通过测量和分析物质在加热或冷却过程中的物理、化学性质的变化,可以对物质进行定性,定量分析,以帮助我们进行物质的鉴定,为新材料的研究和开发提供热性能数据和结构信息. 在差热分析中当试样发生热效应时,试样本身的升温速度是非线性的.以吸热反应为例,试样开始反应后的升温速度会大幅度落后于程序控制的升温速度,甚至发生不升温或降温的现象;待反应结束时,试样升温速度又会高于程序控制的升温速度,逐渐跟上程序控制温度,升温速度始终处于变化中.而且在发生热效应时,试样与参比物及试样周围的环境有较大的温差,它们之间会进行热传递,降低了热效应测量的灵敏度和精确度.因此,到目前为止的大部分差热分析技术还不能进行定量分析工作,只能进行定性或半定量的分析工作,难以获得变化过程中的试样温度和反应动力学的数据.DSC分析与差热分析相比,可以对热量作出更为准确的定量测量测试,具有比较敏感和需要样品量少等特点. DSC分析主要用于研究金属玻璃的显微结构中亚稳相的转变温度以及转变动力学的特征分析.差示扫描量热仪在程序温度控制下测量加载样品和参比物之间的单位时间的能量差(功率差)随温度的变化,记录所得的曲线为DSC曲线.非晶合金是由熔融液态合金急冷得到的,处于热力学亚稳状态,随着温度的升高,必然发生从非晶态向晶态的转变.在转变过程中伴随着放热或者吸热现象：合金在Tg时发生玻璃转变,合金吸热；在Tx时发生晶化转变,合金放热.用差示扫描量热仪对非晶合金进行分析得到DSC曲线,可以测量非晶态样的热稳定性,确定样品的玻璃转变温度Tg、初始晶化温度Txl,和晶化峰值温度Tp;还可以根据曲线分析晶化过程以及结晶焓变△Hx等. 非晶合金中原子是混乱排列的,样品处在亚稳态.当温度升高时,在热激活的作用下,非晶样品结构将发生变化,并伴随着放热和吸热现象.差示扫描量热曲线(DSC曲线)是在差示扫描量热测量中记录的以热流率dH/dt为纵坐标、以温度或时间为横坐标的关系曲线.由非晶合金的DSC曲线可以得到下列的一些信息:(l)玻璃转变温度Tg;(2)晶化温度Tx;(3)结构弛豫峰,并由结构弛豫峰可获得低温结构弛豫和高温结构弛豫,以及它们的弛豫激活能的值;(4)晶化过程以及结晶焓变△Hx;(5)晶化过程中各种亚稳相的信息. DSC曲线主要受实验条件和试样性质的影响： (1) 实验条件的影响 DSC测定中,程序升温速率主要对DSC曲线的峰温和峰形产生影响.一般来说,当升温速率变快时,其DSC曲线的峰温越高,峰面积越大,峰形也越尖锐.这种影响在很大程度上与试样的种类和热转变的类型关系密切.在高升温速率下,会导致试样内部温度分布不均匀.当超过一定的升温速率时,由于体系不能很快响应,试样反应中的变化全貌不能被精确地记录下来,另外,升温速率过快,会产生过热现象.另外为了避免某些待测物质在实验过程中发生氧化、还原等化学反应,不同的物质须在不同的气氛中进行测试. (2) 试样性质的影响 进行DSC测定时 ,一般试样量很少,约为几十毫克.若用量过多,使试样内部传热变慢,温度梯度变大,导致峰形变大,分辨力下降.另外粒度对DSC测定也有一定的影响,但比较复杂.一般来说,颗粒大的热阻较大,使试样的熔融温度和熔融热烩偏低.当结晶的试样研磨成细粒后,由于晶体结构的歪曲和晶粒度的下降也会造成类似的结果.如果粉状试样带有静电,则由于颗粒间的静电引力使粉体团聚,也会导致熔融热焓变大.
璃态转化温度 编辑本义项TG 玻璃态转化温度 TG指玻璃态转化温度,是板材在高温受热下的玻璃化温度,一般TG的板材为130度以上,高TG一般大于170度,中等TG约大于150度. TG值越高,板材的耐温度性能越好 ,尤其在无铅制程中,高TG应用比较多 An important material property often discussed in semiconductor packaging circles is the glass transition temperature, or simply Tg. Below are some key points about Tg: 1) The glass transition temperature (Tg) of a non-crystalline material is the critical temperature at which the material changes its behavior from being 'glassy' to being 'rubbery'. 'Glassy' in this context means hard and brittle (and therefore relatively easy to break), while 'rubbery' means elastic and flexible. 2) Note that the concept of Tg only applies to non-crystalline solids, which are mostly either glasses or rubbers. A glass is defined as a material that has no long-range atomic or molecular order and is below the temperature at which a rearrangement of its atoms or molecules can occur. On the other hand, a rubber is a non-crystalline solid whose atoms or molecules can undergo rearrangement. 3) Non-crystalline solids are also known as 'amorphous materials'. Amorphous materials are materials that do not have their atoms or molecules arranged on a lattice that repeats periodically in space. 4) At room temperature, hammering a piece of glass will break it, while hammering a piece of rubber won't. The rubber would simply absorb the energy by momentarily deforming or stretching. However, if the same piece of rubber is submerged in liquid nitrogen (LN2), it will behave like brittle glass - easy to shatter with a hammer. This is because LN2-cooled rubber is below its Tg. 5) For all amorphous solids, whether glasses, organic polymers, or even metals, Tg is the critical temperature that separates their glassy and rubbery behaviors. 6) If a material is at a temperature below its Tg, large-scale molecular motion is not possible because the material is essentially frozen. If it is at a temperature above its Tg, molecular motion on the scale of its repeat unit (such as a single mer in a polymer) takes place, allowing it to be 'soft' or 'rubbery'. 7) Since the definition of Tg involves atomic or molecular motion, time does have an effect on its value, i.e., the mechanical behavior of an amorphous material depends on how fast a load is applied to it. Simply put, the faster a load is applied to a material at its Tg, the more glass-like its behavior would be because its atoms or molecules are not given enough time to 'move.' Thus, even if an amorphous material is at its Tg, it can break in a 'glass-like' fashion if the loading rate applied to it is too high. 8) In the semiconductor industry, knowledge of the Tg's of the various materials used in packaging (such as die attach materials, molding compounds, and encapsulating resins) is important not only in optimizing manufacturing processes, but in understanding the reliability implications of exposure of the products to thermo-mechanical stresses as well.
差示扫描量热法（differential scanning calorimetry）这项技术被广泛应用于一系列应用,它既是一种例行的质量测试和作为一个研究工具.该设备易于校准,使用熔点低,是一种快速和可靠的热分析方法.差示扫描量热法(DSC)是在程序控制温度下,测量输给物质和参比物的功率差与温度关系的一种技术.DSC和DTA仪器装置相似,所不同的是在试样和参比物容器下装有两组补偿加热丝,当试样在加热过程中由于热效应与参比物之间出现温差ΔT时,通过差热放大电路和差动热量补偿放大器,使流入补偿电热丝的电流发生变化,当试样吸热时,补偿放大器使试样一边的电流立即增大；反之,当试样放热时则使参比物一边的电流增大,直到两边热量平衡,温差ΔT消失为止.换句话说,试样在热反应时发生的热量变化,由于及时输入电功率而得到补偿,所以实际记录的是试样和参比物下面两只电热补偿的热功率之差随时间t的变化关系.如果升温速率恒定,记录的也就是热功率之差随温度T的变化关系. 物质在温度变化过程中,往往伴随着微观结构和宏观物理,化学等性质的变化.宏观上的物理,化学性质的变化通常与物质的组成和微观结构相关联.通过测量和分析物质在加热或冷却过程中的物理、化学性质的变化,可以对物质进行定性,定量分析,以帮助我们进行物质的鉴定,为新材料的研究和开发提供热性能数据和结构信息. 在差热分析中当试样发生热效应时,试样本身的升温速度是非线性的.以吸热反应为例,试样开始反应后的升温速度会大幅度落后于程序控制的升温速度,甚至发生不升温或降温的现象;待反应结束时,试样升温速度又会高于程序控制的升温速度,逐渐跟上程序控制温度,升温速度始终处于变化中.而且在发生热效应时,试样与参比物及试样周围的环境有较大的温差,它们之间会进行热传递,降低了热效应测量的灵敏度和精确度.因此,到目前为止的大部分差热分析技术还不能进行定量分析工作,只能进行定性或半定量的分析工作,难以获得变化过程中的试样温度和反应动力学的数据.DSC分析与差热分析相比,可以对热量作出更为准确的定量测量测试,具有比较敏感和需要样品量少等特点. DSC分析主要用于研究金属玻璃的显微结构中亚稳相的转变温度以及转变动力学的特征分析.差示扫描量热仪在程序温度控制下测量加载样品和参比物之间的单位时间的能量差(功率差)随温度的变化,记录所得的曲线为DSC曲线.非晶合金是由熔融液态合金急冷得到的,处于热力学亚稳状态,随着温度的升高,必然发生从非晶态向晶态的转变.在转变过程中伴随着放热或者吸热现象：合金在Tg时发生玻璃转变,合金吸热；在Tx时发生晶化转变,合金放热.用差示扫描量热仪对非晶合金进行分析得到DSC曲线,可以测量非晶态样的热稳定性,确定样品的玻璃转变温度Tg、初始晶化温度Txl,和晶化峰值温度Tp;还可以根据曲线分析晶化过程以及结晶焓变△Hx等. 非晶合金中原子是混乱排列的,样品处在亚稳态.当温度升高时,在热激活的作用下,非晶样品结构将发生变化,并伴随着放热和吸热现象.差示扫描量热曲线(DSC曲线)是在差示扫描量热测量中记录的以热流率dH/dt为纵坐标、以温度或时间为横坐标的关系曲线.由非晶合金的DSC曲线可以得到下列的一些信息:(l)玻璃转变温度Tg;(2)晶化温度Tx;(3)结构弛豫峰,并由结构弛豫峰可获得低温结构弛豫和高温结构弛豫,以及它们的弛豫激活能的值;(4)晶化过程以及结晶焓变△Hx;(5)晶化过程中各种亚稳相的信息. DSC曲线主要受实验条件和试样性质的影响： (1) 实验条件的影响 DSC测定中,程序升温速率主要对DSC曲线的峰温和峰形产生影响.一般来说,当升温速率变快时,其DSC曲线的峰温越高,峰面积越大,峰形也越尖锐.这种影响在很大程度上与试样的种类和热转变的类型关系密切.在高升温速率下,会导致试样内部温度分布不均匀.当超过一定的升温速率时,由于体系不能很快响应,试样反应中的变化全貌不能被精确地记录下来,另外,升温速率过快,会产生过热现象.另外为了避免某些待测物质在实验过程中发生氧化、还原等化学反应,不同的物质须在不同的气氛中进行测试. (2) 试样性质的影响 进行DSC测定时 ,一般试样量很少,约为几十毫克.若用量过多,使试样内部传热变慢,温度梯度变大,导致峰形变大,分辨力下降.另外粒度对DSC测定也有一定的影响,但比较复杂.一般来说,颗粒大的热阻较大,使试样的熔融温度和熔融热烩偏低.当结晶的试样研磨成细粒后,由于晶体结构的歪曲和晶粒度的下降也会造成类似的结果.如果粉状试样带有静电,则由于颗粒间的静电引力使粉体团聚,也会导致熔融热焓变大.
璃态转化温度 编辑本义项TG 玻璃态转化温度 TG指玻璃态转化温度,是板材在高温受热下的玻璃化温度,一般TG的板材为130度以上,高TG一般大于170度,中等TG约大于150度. TG值越高,板材的耐温度性能越好 ,尤其在无铅制程中,高TG应用比较多 An important material property often discussed in semiconductor packaging circles is the glass transition temperature, or simply Tg. Below are some key points about Tg: 1) The glass transition temperature (Tg) of a non-crystalline material is the critical temperature at which the material changes its behavior from being 'glassy' to being 'rubbery'. 'Glassy' in this context means hard and brittle (and therefore relatively easy to break), while 'rubbery' means elastic and flexible. 2) Note that the concept of Tg only applies to non-crystalline solids, which are mostly either glasses or rubbers. A glass is defined as a material that has no long-range atomic or molecular order and is below the temperature at which a rearrangement of its atoms or molecules can occur. On the other hand, a rubber is a non-crystalline solid whose atoms or molecules can undergo rearrangement. 3) Non-crystalline solids are also known as 'amorphous materials'. Amorphous materials are materials that do not have their atoms or molecules arranged on a lattice that repeats periodically in space. 4) At room temperature, hammering a piece of glass will break it, while hammering a piece of rubber won't. The rubber would simply absorb the energy by momentarily deforming or stretching. However, if the same piece of rubber is submerged in liquid nitrogen (LN2), it will behave like brittle glass - easy to shatter with a hammer. This is because LN2-cooled rubber is below its Tg. 5) For all amorphous solids, whether glasses, organic polymers, or even metals, Tg is the critical temperature that separates their glassy and rubbery behaviors. 6) If a material is at a temperature below its Tg, large-scale molecular motion is not possible because the material is essentially frozen. If it is at a temperature above its Tg, molecular motion on the scale of its repeat unit (such as a single mer in a polymer) takes place, allowing it to be 'soft' or 'rubbery'. 7) Since the definition of Tg involves atomic or molecular motion, time does have an effect on its value, i.e., the mechanical behavior of an amorphous material depends on how fast a load is applied to it. Simply put, the faster a load is applied to a material at its Tg, the more glass-like its behavior would be because its atoms or molecules are not given enough time to 'move.' Thus, even if an amorphous material is at its Tg, it can break in a 'glass-like' fashion if the loading rate applied to it is too high. 8) In the semiconductor industry, knowledge of the Tg's of the various materials used in packaging (such as die attach materials, molding compounds, and encapsulating resins) is important not only in optimizing manufacturing processes, but in understanding the reliability implications of exposure of the products to thermo-mechanical stresses as well.