Eight, brazing
Since the heat input to the soldering is optional, it opens up new avenues for laser beam soldering in the encapsulated ceramic glass housing applications in the electronics industry. Brazing tests on alumina substrates, on D263 glazing (borosilicate glass) flat glazings and on two flat glazings with glass varnishes of comparable expansion coefficients, show that the brazed joints do not have any Crack, low porosity, good sealing, no leakage of helium.
Arc bolt brazing (ASB) has reached a stage suitable as a manufacturing connection technology. For example, it has now been applied to steel plates and bolts that are joined to high carbon steel. In ordinary welding, the parts become harder and brittle, and even for bolts with a diameter of 16 mm, the penetration depth is actually zero. The ASB greatly reduces the hydrogen-induced cracking, and the hardness is increased due to the presence of the intermetallic phase, so that bolting can be performed between the non-alloy steel and the alloy Cr-Ni steel.
Initial tests have shown that even Cr-Ni bolts can be brazed to aluminum sheets. Arc bolt brazing can also be carried out using the same equipment technology as bolt welding, especially for short-term lifting and arcing. In arc bolt brazing, unlike arc welding, arcs create a common weld pool between the connected parts.
The following examples illustrate the possibilities of ASB applications.
For example, for 0.81% of 9ISZV rail material, ASB welding with foil solder has achieved good results. In the tensile and bending tests, the test piece is damaged, the bolt is not affected, and it can be bent. To 90o; the other is the use of arc bolt brazing used in the building supervision department has also achieved good results. Using ASB technology, it is even possible to braze φ16mm "black" bolts to "white" steel plates (Cr-Ni, thickness 2.5mm). When the thickness of the sheet reaches 1.5 mm, the strength of the ASB joint is lower than that of the bolt, but higher than that of the ordinary flame brazed joint. When the plate thickness is >1.5 mm, the strength of the ASB joint is the same as that of the bolt welded joint between the same materials. Comparing these two welds, the heat input required for arc bolt brazing is greatly reduced, the penetration is greatly reduced, and the strength is high, even for steels that are sensitive to increased hardness.
With the increase of magnesium as a manufacturing material, brazing technology has also been developed correspondingly, and AZ91A and AZ31 are used as matrix materials. According to the test results of the flooding experiment, the Mg-Zn alloy can be used as a brazing filler metal, and different pure metal foils are used as a consumable material for the spot brazing test. Studies have shown that brazing AZ91A materials can be joined with Mg-Zn brazing solder. For spot brazing, aluminum foil is the most suitable consumable material.
In order to braze alumina and metal, a palladium-based high-temperature brazing alloy has also been developed. In addition to high melting temperature (1555 ° C) and oxidation resistance, palladium can form crystals with many elements, which makes it possible to develop solders as needed. Chromium, vanadium, titanium and niobium can be added as alloying elements. In the process of brazing alumina (Al300 containing 97.6% Al2O3 and adding CaO and SiO2 as metallurgical powder; Al997 containing 99.7% Al2O3), the infiltration characteristics and brazing characteristics of palladium brazing alloy were studied experimentally. . For this purpose, not only metal foils are produced using Pd-6Cr, Pd-10Cr and Pd-6V brazing alloys, but also pure palladium, titanium, tantalum, vanadium and chromium element brazing alloys are used to make metal foils.
Due to the problem of oxidation, it is impossible to clearly understand the wetting characteristics of the alloy metal foil. It seems that Al 997 can be infiltrated, while AI 300 can't. In sharp contrast, alloys made with Al 300 in the field exhibit good wetting characteristics, and all brazing alloys achieve high joint strength at room temperature. Joints welded with Pd-6Cr are resistant to high temperatures of 1000 °C.
Since the heat input to the soldering is optional, it opens up new avenues for laser beam soldering in the encapsulated ceramic glass housing applications in the electronics industry. Brazing tests on alumina substrates, on D263 glazing (borosilicate glass) flat glazings and on two flat glazings with glass varnishes of comparable expansion coefficients, show that the brazed joints do not have any Crack, low porosity, good sealing, no leakage of helium.
Arc bolt brazing (ASB) has reached a stage suitable as a manufacturing connection technology. For example, it has now been applied to steel plates and bolts that are joined to high carbon steel. In ordinary welding, the parts become harder and brittle, and even for bolts with a diameter of 16 mm, the penetration depth is actually zero. The ASB greatly reduces the hydrogen-induced cracking, and the hardness is increased due to the presence of the intermetallic phase, so that bolting can be performed between the non-alloy steel and the alloy Cr-Ni steel.
Initial tests have shown that even Cr-Ni bolts can be brazed to aluminum sheets. Arc bolt brazing can also be carried out using the same equipment technology as bolt welding, especially for short-term lifting and arcing. In arc bolt brazing, unlike arc welding, arcs create a common weld pool between the connected parts.
The following examples illustrate the possibilities of ASB applications.
For example, for 0.81% of 9ISZV rail material, ASB welding with foil solder has achieved good results. In the tensile and bending tests, the test piece is damaged, the bolt is not affected, and it can be bent. To 90o; the other is the use of arc bolt brazing used in the building supervision department has also achieved good results. Using ASB technology, it is even possible to braze φ16mm "black" bolts to "white" steel plates (Cr-Ni, thickness 2.5mm). When the thickness of the sheet reaches 1.5 mm, the strength of the ASB joint is lower than that of the bolt, but higher than that of the ordinary flame brazed joint. When the plate thickness is >1.5 mm, the strength of the ASB joint is the same as that of the bolt welded joint between the same materials. Comparing these two welds, the heat input required for arc bolt brazing is greatly reduced, the penetration is greatly reduced, and the strength is high, even for steels that are sensitive to increased hardness.
With the increase of magnesium as a manufacturing material, brazing technology has also been developed correspondingly, and AZ91A and AZ31 are used as matrix materials. According to the test results of the flooding experiment, the Mg-Zn alloy can be used as a brazing filler metal, and different pure metal foils are used as a consumable material for the spot brazing test. Studies have shown that brazing AZ91A materials can be joined with Mg-Zn brazing solder. For spot brazing, aluminum foil is the most suitable consumable material.
In order to braze alumina and metal, a palladium-based high-temperature brazing alloy has also been developed. In addition to high melting temperature (1555 ° C) and oxidation resistance, palladium can form crystals with many elements, which makes it possible to develop solders as needed. Chromium, vanadium, titanium and niobium can be added as alloying elements. In the process of brazing alumina (Al300 containing 97.6% Al2O3 and adding CaO and SiO2 as metallurgical powder; Al997 containing 99.7% Al2O3), the infiltration characteristics and brazing characteristics of palladium brazing alloy were studied experimentally. . For this purpose, not only metal foils are produced using Pd-6Cr, Pd-10Cr and Pd-6V brazing alloys, but also pure palladium, titanium, tantalum, vanadium and chromium element brazing alloys are used to make metal foils.
Due to the problem of oxidation, it is impossible to clearly understand the wetting characteristics of the alloy metal foil. It seems that Al 997 can be infiltrated, while AI 300 can't. In sharp contrast, alloys made with Al 300 in the field exhibit good wetting characteristics, and all brazing alloys achieve high joint strength at room temperature. Joints welded with Pd-6Cr are resistant to high temperatures of 1000 °C.
Adopted high-molecular synthetic resin bond, high-strength bonding, water and high-temperature resistance, special anti-clog coating surface, with Good self-cleaning performance and good chip removal ability, which can avoid clogging the abrasive grains, and maximum improve the performance of sandpaper.
High Coating Abrasive Paper,Waterproof Paper,Fine Abrasive Paper,Emery Paper Disc
ZHENJIANG DINGHUI ABRASIVE TOOLS CO.,LTD , https://www.dhabrasivepaper.com