Applying Of The Development Of Soldering Paste For Polycrystalline Diamond

The polycrystalline diamond compact bits were widely applied in many fields including petroleum industry、geological prospecting industry and natural gas industry because of its high drilling efficiency.This kind of bits was made of polycrystalline diamond and high-strength steel.The polycrystalline diamond bits were made by using manual flame brazing.This way is of low efficiency.It will cause the workpiece to be scrapped if workers use high brazing temperature.The high frequency welding has many advantages such as high heating rate and we can control the brazing temperature.At the same time,we can finish weld all diamonds at the same time.We can use this way to replace the traditional method.This will be a new hot topic in this fields.However,the new brazing filler metal need to be find to match the high heating rate.The traditional silver filler metal can not satisfy the practical requirements and the new brazing filler metal need to be developed.A new silver base brazing paste has been developed which is suitable for high frequency induction brazing in this article.It can satisfy the need of high efficiency、low cost and high quality.Research achievements in this paper replenish blank space of brazing grease for stainless steel-aluminum high frequency induction brazing at home and abroad and have tremendous social and economical advantages.According to the weight percentage,it was made of 75%~80% alloy powder、10%~14% fluoride flux、7%~8% saturated aqueous solution of sodium silicate、2%~3% white oil、1%~2% alkylphenol polyoxyethylene ether.Under the condition of the atmosphere,the diamond bit can be welded all at once and efficiently by using this new type of brazing paste.It has good storage performance.It can be reserved without hardening and hierarchy in a month by sealed in glass containers.A new solder paste will be developed for a period of time,and then observe the changes of physical and chemical properties.In the specified period of time to detect the use of performance,the development of a new type of solder paste reached the required level.Developed solder paste on the wettability,filling clearance ability,brazed joint mechanical properties,brazing holding time and brazing seam microstructure and other indicators reached the level of solder powder,and the operation process with good performance,in the high frequency induction heating does not produce sputtering.Long term storage is not dry solid,not failure.The results of many performance tests show that it has the good wettability on the surface of both side after 700℃.The wetting angle is less than 20°at this moment.When the thickness of spacer is less than 2mm,it can fill the entire weld laterally.In the climbing tests,the weld joint can be filled over 25 mm when the thickness is 1.2mm and over 10 mm when the thickness is 2.0mm.At the same time,the welding joint has the very high intensity.In the mechanical properties testing,the fracture locations all appear in the parent metal.The result of microscopic analysis shows that elements transite smoothly such as Al and Cu near the parent metal and the apparent welding defect was not found.Finally,we have found the most suitable welding process parameters to this new brazing paste are as follows:(1)brazing temperature: 680~700℃(2)brazing holding time(3)brazing clearance: 0.1~0.5mm(4)brazing stress: 2.0MPa~4.0MPa.