工业的核心，几乎没有任何东西可以不经过热处理而制造出来. 我们最近采访了Bob Farrell (Hubbard-Hall的高级副总裁兼技术总监)，并向他询问了一些关于热处理市场的问题, 他在30年的经验中所看到的以及使用这些澳门威尼斯人网上赌场的制造商的前景.
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Why are metals heat treated?
Metals are crystalline materials; there are rare cases where they could be amorphous, but generally speaking, metals are crystalline materials. By heating a metal, 你可以改变这种金属的晶体结构，得到某些想要的特性，比如硬度. Most people are familiar with the Rockwell Hardness; for instance, 你做一个转换结晶转换, and then you try to lock that in, or you try to cool it, 所以它更多地转变到一个不同的阶段，并锁定那个阶段. You could get characteristics such as hardness or toughness; in some cases — although we’re not involved really in salts to do that — you can also infuse materials into the surface of the metal and form what’s called ‘the case.’ You could have a nitrogen case, a carbon case, 黑色氧化物是将贱金属材料转化为该贱金属材料的氧化物. A prime example would be Fe3O4, which is black iron oxide, otherwise known as magnetite; another is a CuO, or copper monoxide. 当化学物质与基础物质反应形成基础主要成分的氧化物时，就会发生这种反应. In the case of stainless steel, not only does it form oxides, 但它也会形成基材的硫化物，这些硫化物往往也是黑色的. or a carbon nitride case. 这些类型的表面也可以提供润滑性, but generally speaking, 你在做所谓的中性硬化，然后回火，以获得特定的晶体结构，从给定的金属中获得特定的特性.
What are heat-treating salts?
Salts are blends of common salts; for instance, 所谓的“高温盐”是钾和氯化钠的混合物. 如果它是一个熔点很高的盐你在更高的温度下工作你也可以在里面放氯化钡, 所以氯化钾钠和氯化钡存在于一种盐中这是一种中性盐它通常也被称为高温盐. 你可以加入回火盐, 通常在低于1000华氏度的温度下工作，但至少在熔点以上50华氏度到100华氏度. 回火盐是亚硝酸钠、硝酸钠和硝酸钾的混合物. 有一种盐是卖给铝热处理的那就是硝酸钠和硝酸钾. 有硝酸盐，也就是回火盐，还有高温盐, which are your chloride salts. What the salt is it’s a dry powdered blend, but you heat it to its melting point, and then it becomes a liquid. It’s a melt just like ice melts, and you have water; it’s the same thing with the salts.
Why use heat treat salts?
用于热处理金属的方法是盐或熔炉，你可以把零件放在传送带上进入高热熔炉, 只是周围的空气加热了这些部件. So the parts will come out, 然后你做一个淬火来冷却它们，试图锁定一个结构，或者冷却它们，然后把它们加热到一个通常在300到800华氏度之间的范围, and temper back the metal. 这可以在很多零件上完成，比如紧固件，小零件. 真正使用盐的地方是你想要很少变形的地方. 如你所知，如果你加热某样东西然后迅速冷却，它就会变形. 盐，因为它们是相对致密的液体，减少了热处理过程中的变形量. Therefore salts are used on things such as precision gears; lawnmower blades are a huge area where salts are used primarily for distortion purposes. 当你观察熔盐时，盐在做什么? 它有两种用途:一种是给某个部位增加热量，另一种是把热量从某个部位带走, such as in a quench. If you remember thermodynamics, heat flows from hot to cold, so if you have a hot salt, 热量流入零件，将其加热到中性硬化的温度, and then that could go into a quench, and the salt is cooler than the part. 当它放进去的时候，热量从部分回到盐里. 盐吸收热量的程度和速度比空气要大得多如果你用空气淬灭的话, which some people do out of furnaces.
What types of heat-treating salts are there?
To summarize, 有三种基本类型的盐:回火盐是在300°F到900°F范围内工作的盐，这些盐通常用于加热部件，如果部件在该温度范围内发生相变，或者将部件冷却到该温度范围并锁定部件的晶体结构. 你有中性盐，通常在1000°F以上使用，更典型的是在1500°F到1800°F的范围内使用，可能高达2100°F，用于中性硬化. The third salt are the case hardening salts; you don’t see them used as frequently anymore, 但是如果你有一个零件你想要低变形但你想在零件上做碳或氮或碳氮结合的情况，这是一个非常薄的层，你可以使用渗碳或表面硬化盐. 目前仍在使用的盐类有三种.
Are all tempering salt compatible?
They are if they’re nitrate-based salts. The difference between the salts are the ratios; the ratios determine what the melting point is. 有一种盐有共析混合物，它的熔点精确到275华氏度. 然后你可以有盐，比如用于铝的盐，它是钾和硝酸钠，在420华氏度融化. 所有的硝酸盐盐都含有三种碱性氮, which are sodium nitrate, potassium nitrate, and sodium nitrite. You can, in theory, use them together, 但是你会改变熔点因为你的比例会改变. They could be mixed, 但是它们不能给你精确的熔点，这很重要, and it also changes the heat You can, in theory, use them together, 但是你会改变熔点因为你的比例也会改变盐的吸收或者传热特性.
高热浴的整改是做什么的，又该怎么去加颗粒呢?
高温浴反应是因为它们与空气中的氧气和二氧化碳发生反应. You can imagine you have this molten solution of salts; it’s glowing red, 它在浴缸中与二氧化碳和氧气反应形成碳酸盐, but it also forms oxides in the bath. 当你得到这些会发生什么呢?它会干扰热量传递, 这可能会给零件的冶金制造带来一些困难. 你要做的就是净化，去除那些氧化物, and that’s typically done with pellets, 或者像过去那样，人们会在盐中泡出氯甲烷气体来纠正它. 整流器真正要做的是消除那些在那里形成的氧化物并中和碳酸盐. The pellets generate ammonia in the salt, so you want to add the pellets slowly, and of course, with any rectification, 你可以在工作人员不在洗澡时进行整改. 你在进化氨它会中和碳酸盐并与氧化物反应. 确保在通风良好的地方进行，这样就不会有可能形成的气体逃逸到工作环境中.
去除高温浴和回火锅的污泥的最好方法是什么?
去除污泥的最佳方法是将其冷却到尽可能接近熔点的温度，在熔点50°F到100°F之间. 你要做的是清除淤泥你在回火盐上看到的更多你从高温浴中出来那是氯化物浴，盐的熔点达到1000华氏度或更高, 然后你进入一个低于熔点的回火棒. 盐中性盐会在回火盐中脱落, and of course, 它们在回火浴的温度下不会融化, so those salts will come out, and it’ll precipitate out in the form of sledge. 你要做的就是把回火浴冷却到275华氏度的温度, you cool it down to say 350°F, and then you go in, and you ladle out the sludge that’s falling out. It’s almost like snow falling; imagine your tempering salts in the atmosphere; the chloride salts the snow that falls down and accumulates at the bottom of the pot, and you take it out. 被拖进高温浴的污染物——比如工作不够干净，或者上面有很多沙砾、污垢或颗粒物质——也可能在中性浴中形成这些污泥, the high-temperature neutral bath, and see the same thing. 假设盐浴的熔点是1000华氏度, 你会把它冷却到1075华氏度，然后慢慢地，非常小心地, of course, 进去，试着从盐浴的底部舀出污染物，把它们舀出来.
贵公司有能力对盐浴进行分析吗?
我们定期为客户做盐浴分析. In some cases, it’s paid for, and in some cases, it’s not, 但是我们有能力做高温中性盐和回火盐.
你们提供的几种回火盐的区别和优点是什么?
There really isn’t much difference. 这都取决于你想在什么温度下操作. 除了用在铝上的盐, 这种盐是非常特殊的因为你不希望亚硝酸盐出现在用于铝的盐中. So, it really depends on the factors that come into play; and of course the cost of the salt — sodium nitrite being the most expensive ingredient that’s typically in there — but it’s also the ingredient that gives you a lower melting point. I recommend a 275°F melt point; it’s a very precise melt point and it gives you an operating range of up to 1000°F. The salt could be used for a lot of applications; if you want a less expensive salt, 你可以用300华氏度的盐来代替, but generally speaking, 总之，回火盐的吸热和热传导特性并没有太大的区别.
Where do I send samples for testing?
我们在南卡罗来纳的英曼工厂进行测试. They’d be sent into the attention of Dr. 道格拉斯·巴顿，他为我们做了所有的盐和盐分析.
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