The preparation of sample of metallographic of welding line of makings of precious metal drill rod

Technology of solder of foreword drill rod is to solder now the field is main one of component, because drill steel of precious metal alloy expects (silver-colored alloy, gold alloy and palladium alloy are fastened) capable person of mother of drill rod solder is extensive, contact intensity tall, plasticity is good, be able to bear or endure strong, heat-resisting pounds corrode sex the gender is admirable, because of AuNi18 of this such as, pdAgMn, pdNi, the department alloy such as AgCuZn and AgCuZnCd won wide application in aviation engine workmanship. In quality inspection of connect of drill rod solder, metallographic of connect of drill rod solder examines have important place, about precious metal drill rod makings connect metallographic erodes a method to have not see systematic story. The article expects with precious metal drill rod in the light of Si Bei engine characteristic and its rule do the preparation of the metallographic sample of connect of solder of alloy drill steel to be discussed. The welding line structure of model of drill rod weldment is shown like plan institute. Can see by the graph, welding line is comprised by 5 different structures, as a result of precious metal alloy be able to bear or endure corrode sex and difference of mother capable person are bigger, be about to show the metallographic organization with 5 all clear structures, in metallographic sample preparation, should note following characteristics. Sketch map of welding line structure 　 (1) alloy of makings of precious metal drill rod, especially golden radical drill rod expects relatively mother capable person (material of blame precious metal) anti-corrosive much. (2) from the organization stability angle looks, the drill rod makings in welding line is sketch map of structure of the welding line on casting graph hair voice, and capable person of two kinds of mothers is in anneal condition basically below action of high temperature of drill rod solder, the organization is stabler, consequently makings of the drill rod in welding line is corroded easily and capable person of mother of layer of two side anneal is corroded hard. (3) to save precious metal, weldment sample is normally lesser, secure not easily, must use special type clamping apparatus or set prototype to secure weldment, make place easily hold, right not the brittleness of compression and ultrathin weldment consider to use even cold set a standard. In addition, grinding welding line place should avoid to appear as far as possible in throwing a process horn and anaglyph. (4) very hard choice goes one kind suits at the same time and can clear of the metallographic organization structure that shows 3 kinds of stuff erode an agent. According to drill rod of preparation gold, silver-colored, palladium radical makings alloy drill steel solders the experiment of sample of metallographic of head welding line, we found the method of the microstructure of welding line of makings of drill steel of precious metal alloy that can get clarity. 2.

Experimental method 　 (1) choose 4 kinds of drill rod to expect, its composition is Ag24Cu43Zn33, pd20Ag5Mn75, compound drill rod of Ag71Cu28Ni1 and AuIn expects. (2) capable person of mother of drill rod solder is the copper that do not have oxygen, stainless steel, aureate but cut down alloy. (3) erode agent and its recipe. Because experiment to all be with alloy,contain precious metal, anti-corrosive with much group yuan drill rod makings, because this is eroded,the agent should choose those who contain strong acid alkali to deserve to compare. Through eroding a law to chemistry, electroanalysis erode law and different type erode an agent to undertake filtration, single out a few kinds when express a kind to erode agent and its recipe from which. 3.

Test result and discussion 　 (1) the choice result rank that expects by experiment drill rod the welding line metallographic of alloy and composition of different mother capable person erodes an agent is expressed 2, by afore-mentioned metallographic that erode methodological preparation the organization is shown at the graph 1 ～ pursues 5. Test result makes clear, the chemistry that uses this experiment option erodes a method to be able to obtain metallographic of clearer connect of drill rod solder to organize. 5 AuIn of graph of × of 120 of welding line of makings of compound drill rod of 4 In/Au/In of graph of × of 120 of welding line of makings of drill rod of 3 Ag71Cu28Ni1 of graph of × of 23 of welding line of makings of drill rod of 2 Pd20Ag5Mn75 of Nextpage graph of × of 10 of welding line of makings of drill rod of graph 1 Ag24Cu43Zn33 　 of 　 of × of 20 of welding line of drill rod makings (2) alloy of makings of precious metal drill rod is more anti-corrosive, need to use alkali, strong acid, strong oxidant to erode commonly organize in order to show drill rod makings is microcosmic, and mother capable person is material of blame precious metal, not anti-corrosive, easy below action of strong acid alkali oxidation is nigrescent; in addition, makings of the drill rod in welding line is casting condition, the organization is not stable, and mother capable person is anneal condition, the organization is stabler. Integrated these characteristics, the choice that erodes an agent should display the microcosmic organization that drill rod expects more quickly, and do not make mother capable person is oxidized, show its at the same time microcosmic organization. (3) in electroanalysis in eroding a law, because connect of drill rod solder punishs drill rod makings and mother capable person all at the same time immerge electrolyte (erode an agent) in electroanalysis, because mother capable person is blame precious metal, electrode potential is low, to drill rod makings precious metal forms protection, and oneself is used up, reason cannot get clear welding line metallographic, do not use 　 of this kind of method commonly (4) when the metallographic sample that in preparation You Guijin belongs to connect of solder of drill rod of drill rod makings, as a result of the complexity of welding line structure, need to be chosen according to the particular case of weldment different metallographic enchases pink or use special type clamping apparatus. To softer alloy polish when, the rotate speed that casts CD should be used slow fast, when necessary need not polishing creams, make welding line surface bright and clean before was not eroded as far as possible level off. 4.

Conclusion 　 (1) contain Au clearly to obtain, the drill steel of precious metal alloy such as Pd and Ag expects welding line metallographic is organized, the preparation of metallographic sample should use chemical law to erode. CNC Milling