大连数控加工中铝外貌发黑原因是铝制品被氧化而发黑，建议不扫除，氧化铝在空气中较为稳固！：
：：苣言傺趸！？梢员；
；；つ诓康穆敛槐谎趸！ 铝：
：：银白色轻金属！Ｓ醒诱剐！Ｉ唐烦Ｖ瞥砂糇、、、片状、、、箔状、、、粉状、、、带状和丝状！Ｔ谑罂掌心苄纬梢徊惴乐菇鹗羟质吹难趸！

铝粉和铝箔在空气中加热能强烈燃烧，并发出眩目的白色火焰！Ｒ兹苡谙×蛩、、、硝酸、、、盐酸、、、氢氧化钠和氢氧化钾溶液，难溶于水！Ｏ喽悦芏2.70！Ｈ鄣660℃！７械2327℃！Ｂ猎卦诘乜侵械暮拷龃斡谘鹾凸，居第三位，是地壳中含量最富厚的金属元素！：
：：娇、、、修建、、、汽车三大主要工业的生长，要求质料特征具有铝及其合金的奇异性子，这就大大有利于这种新金属铝的生产和应用，应用较为普遍！

The reason for the blackening of aluminum surface in Dalian CNC machining is that aluminum products are oxidized and blackened, and it is recommended not to remove them. Aluminum oxide is relatively stable in air. It's difficult to oxidize again. It can protect the internal aluminum from oxidation. Aluminum: Silver white light metal. Has extensibility. Products are often made into rods, sheets, foils, powders, strips, and filaments. A layer of oxide film can be formed in humid air to prevent metal corrosion.

Aluminum powder and aluminum foil can burn fiercely when heated in the air, emitting dazzling white flames. Easy to dissolve in dilute sulfuric acid, nitric acid, hydrochloric acid, sodium hydroxide, and potassium hydroxide solutions, but difficult to dissolve in water. The relative density is 2.70. Melting point 660 ℃. Boiling point 2327 ℃. Aluminum is the third most abundant metal element in the Earth's crust, after oxygen and silicon. The development of the three important industries of aviation, construction, and automobiles requires materials with unique properties of aluminum and its alloys, which greatly facilitates the production and application of this new metal aluminum and has a wide range of applications.