电阻丝的选用需考虑材料允许的表面功率，电热丝的截面面积，电热丝的长度，电热丝的形状（直行、螺旋、折线、缠绕等）等。
电热丝的一个重要参数，就是表面功率。电阻率过大，通入一定电流后，表面功率也就大。所以小功率的电器，就选用小直径小电流，但是电流的大小决定于电阻的大小，电热丝的长度和直径就是经过计算的。所以电热丝就是在设计电热器时要功率多方面的因素。材质选择 根据电加热管的工作温度可分为超高温级电加热器、高温级电加热器、中温级电加热器、低温级电加热器。加热管的温度是由加热丝提供的所以根据工作温度不同加热丝的选用如下。1）超高温级电加热器超高温级电加热器的使用温度为1400℃。它用于制造工作温度为1200~1300℃加热炉用的电热元件。该合金的化学成分全都属于铁铬铝系。电热管为了保证合金在高温时的使用性能，这一组合金中含有较高的铬和铝。其中铬22%~28%，铝6%~8%，还含有少量的钴、钼、铌、钛和微量的钇、镧、鈰等元素。这组合金中包括利用粉末冶金法制造的钢胚、加工制造的电加热器线、带材。超高温电加热器主要用于工作温度在1200~1300℃ 的单晶体扩散炉、粉末冶金制品烧结炉、陶瓷煅烧炉和高温热处理炉等的电热元件。2）高温级电加热器高温级电加热器的使用温度为1300℃，主要用于制造温度在1100~1200℃加热炉用电热元件。这一组电加热器也都属于铁铬铝系列。该组合金中铬、铝含量稍低于超高级合金，含铬22%~25%，铝4%~6%，也含有少量钼、铌、钴、钛和稀土元素。 属于高温级电加热器牌号有0Cr25Al5、0Cr21Al6Nb、0Cr23Al6等。3）中温级电加热器中温级电加热器使用温度为1100℃，主要用于制造工作温度为850~950℃加热炉用电热元件，这一组电加热器具有较好的塑性，在常温下可加工制成形状复杂的电热元件。属于此类的电加热器牌号有：镍铬系合金Cr30Ni70；Cr20Ni80，铁铬铝系列合金0Cr23Al5，0Cr20Al3，0Cr19Al5，0Cr21Al6等。4）低温级电加热器低温级电加热器的使用温度为950℃以下，主要用于制造工作温度在800~750℃以下的加热炉用电热元件，例如低温回火炉，烘干炉以及家用电器等。属于此类的电加热器有：镍铬系中的Cr15Ni60，Cr20Ni35，Cr20Ni25合金和铁铬铝系合金的1Cr13Al4，0Cr19Al3等
Selection of resistance wire surface of the material allows the power, the cross section area of the heating wire, the length of the heating wire, the shape of the heating wire (straight, spiral, polylines, winding, etc.), etc.
An important parameter of the heating wire, power is surface. Resistivity is too large, into a certain current, surface power is large. So small power electrical appliances, to choose small diameter small current, but the size of the current is determined by the size of the resistance heating wire length and diameter is calculated. So in the design for electric heater, electric heating wire is going to power a variety of factors. The material selection According to the working temperature of the electric heating pipe can be divided into levels ultra high temperature electric heaters, high temperature level temperature in an electric heater, electric heater, low temperature electric heater. The temperature of the heating tube is provided by the heating wire so according to the selection of different heating wire working temperature is below. 1) levels ultra high temperature electric heater ultra high temperature electric heater temperature is 1400 ℃. It is used in the manufacture of working temperature is 1200 ~ 1300 ℃ heating furnace with electric heating element. The chemical composition of the alloy are all belong to the iron chromium aluminum system. In order to guarantee the use of the alloy at high temperature performance, the combination of gold containing high chromium and aluminum. 22% ~ 28% of chromium, aluminum 6% ~ 8%, also contains a small amount of cobalt, molybdenum, niobium, titanium and trace element yttrium, lanthanum, cerium, etc. This combination of gold include powder metallurgy method is used to manufacture steel embryo, processing and manufacturing of electric heater wire, strip. Electric heater is mainly used for high working temperature at 1200 ~ 1300 ℃ of single crystal diffusion furnace, powder metallurgy products, sintering furnace, ceramic calcine furnace heating elements and high temperature heat treatment furnace, etc. 2) levels of high temperature electric heater temperature of electric heater temperature is 1300 ℃, mainly used in the manufacture of temperature at 1100 ~ 1200 ℃ heating furnace with electric heating element. This set of electric heater is also belong to the iron chromium aluminum series. This group of chromium, aluminum content in the alloy was slightly lower than senior alloy, chromium containing 22% ~ 25%, 4% ~ 6% aluminum, also contain small amounts of molybdenum, niobium, cobalt, titanium and rare earth elements. Level belongs to the high temperature electric heater brands have 0 cr21al6nb cr25al5, 0, 0 cr23al6, etc. 3) levels of temperature in the electric heater temperature electric heater temperature is 1100 ℃, mainly used in the manufacture of working temperature is 850 ~ 950 ℃ heating furnace with electric heating element, a set of electric heater has good plasticity, at room temperature for processing complicated shape electric heating element. Belong to this kind of electric heater brand are: nickel chrome alloy Cr30Ni70; Cr23al5 Cr20Ni80, iron chromium aluminum alloy series 0, 0 cr20al3, 0 cr19al5, 0 cr21al6, etc. 4) levels low temperature electric heater temperature for the use of electric heater temperature below 950 ℃, mainly used in the manufacture of working temperature at 800 ~ 750 ℃ under heating furnace with electric heating element, such as low temperature tempering furnace, drying furnace, and household electrical appliances, etc. Belong to this kind of electric heater are: nickel chrome Cr15Ni60 of Cr20Ni35, Cr20Ni25 iron chromium alloy and aluminum alloy 1 cr13al4, 0 cr19al3,
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