Ferrochrome for glass sealing

Posted by Wangkiky Wangkiky over 6 months ago

Ferrochrome alloy used for glass sealing is ferrochrome alloy with 28% chromium, also known as high chromium steel or 28 expansion alloy. Due to the addition of chromium, the expansion coefficient of the alloy is reduced, so it can be matched with soft glass for sealing.[url=http://www.anticorrosionsteel.com/sheet-plate/4333.html]ms carbon steel pipe fitting 90 degree elbow[/url] , Ferrochromium alloy with high chromium content will be ferrite in the whole range from room temperature to melting point temperature, so it is also called ferritic ferrochromium alloy. Before sealing, the alloy needs to be heated to 950 ℃ in wet hydrogen to form a gray green, thin and dense oxide layer of CrO3 and Fe2O3 on the surface, which can dissolve into the glass and form a grass green or brown green sealing surface. The characteristic of this alloy is that the phase transformation point is very high because the chromium content is more than 28%. The second anode lead cap of the general picture tube and the cone head of the shadow mask frame fixed on the screen of the color picture tube. The deflection electrode needle of the circular scanning oscillograph and the tube needle of the disk core are made of high chromium steel. In the past, when the pressing process of the glass cone of the picture tube was not solved, the metal cone was made of high chromium steel and then sealed with the glass screen, which can be seen in some old picture tubes. However, it must be noted that when heated to 800-1200 ℃, austenite iron will be produced. The coefficient of expansion of this kind of austenite is much larger than that of ferritic ferrochromium alloy, and it can still be stably stored in the alloy at a lower temperature. In this case, the coefficient of expansion will change, and the risk of abnormal coefficient of expansion characteristic curve will appear, The material is not suitable for glass sealing. Therefore, great attention must be paid to the appearance of austenite in ferrochromium alloys with ferrite, whether in smelting or in use.[url=http://www.anticorrosionsteel.com/sheet-plate/5624.html]cheap 316Ti 4x8 stainless steel perforated sheet[/url] Ferrochrome has no danger of oxidation. The green to mouse gray chromium oxide and iron oxide surface layer produced by ferrochrome are very firmly attached to the alloy wire, and further oxidation can be prevented in the sealing process.[url=http://www.alloysteelasia.com/steel-supply/223.html]Tianjin steel factory Supply SS400 A36 mild carbon steel flat[/url]