The intensity of Si₃N₄ of chemical plating nickel and connect of solder of metallic drill rod studies

1 test data and equipment ceramics choose pottery and porcelain of hot pressing Si3N4, dimension is 10 Mm of × of 10 Mm of 10 Mm × , the metal uses Q235 board, dimension is 2 Mm of × of 30mm of 30 Mm × , drill rod makings is BAg72Cu-V. Chemical plating undertakes in chamfer of constant temperature of bath of CS-501 super water, drill rod solder uses self-restrained glow heat (power is 3 KW, working voltage is 0 ～ 1000 V, ultimate pressure can be amounted to 0.

1Pa, vacuum cubage is 0.

026 M3, working gas is 99.

) of 99% industry pure argon. 1.

The method that 2 experiments method uses chemical plating makes surface of Si3N4 pottery and porcelain forms the nickel film of certain ply, become apparent of pottery and porcelain learns plating technological process is as follows: The preparation of test block of pottery and porcelain, rigid standard is thick change the face, organic dissolvent removes oil, alkaline degreasing, chemistry is thick change, sensitize, activation, reductive, chemical plating nickel. Reach makings of plating nickel pottery and porcelain, drill rod burnish of Q235 armor plate, solder of glow drill rod is loaded after cleaning furnace. Vacuumize is spent to 0.

1Argon is filled to rise after Pa brightness, with average 50 ℃ / Min rate warms up to 850 ℃ , after heat preservation 8 Min, with average 25 ℃ / the rate of Min is cold to 300 ℃ , last furnace is cold to room temperature. Use WD-100 electron universal test machine undertakes to connect of drill rod solder shear strength experiments. The experiment uses special fixture, cut speed to be 1 Mm/min. Shear strength presses τ B=Pb/A computation, among them the load when Pb is destroyed for contact, a cuts an area to suffer. With electron microscope of metallographic microscope, scanning, can the small area of the butt joint head such as chart appearance and X diffraction appearance undertakes an analysis. The micromechanism of connect of solder of 2 drill rod and interfacial reaction pursue distributinging spectral line of the electric lens image of pottery and porcelain of Si3N4 of the 1 nickel that it is plating and connect of solder of drill rod of Q235 armor plate and element, graph the 2 elements that are this connect distributing graph. (　 of 1nextpage of graph of distributinging spectral line of element of 500 (b) of × of appearance of form of union of armor plate of Si3N4-Q235 of A) plating nickel from the graph 1 with the graph 2 see apparently, connect of plating nickel Si3N4-Q235 is more than 1 complex structures, the area that existence wears 4 to differ (pottery and porcelain, film, brazed seam and metallic mother capable person) with 3 interfaces (Si3N4/Ni, Ni/Ag-Cu, Ag-Cu/Fe) . 2 interfaces all are belonged to after normally the union between brilliant of drill rod solder, have better strength and plasticity commonly, the combinative means of Si3N4/Ni interface sets union and chemical band for machinery. Graph the Si3N4 pottery and porcelain of nickel of plating of distributinging graph chemistry is in the element of connect of steel of Si3N4-Q235 of 2 plating nickel in the process of solder of glow drill rod, in drill rod solder vacuum is spent and temperature of drill rod solder falls, plating Ni layer and place of interface of Si3N4 pottery and porcelain meet those who produce Ni and Si diffuse see a picture 2, the Ni of certain content is had in side of pottery and porcelain, explain Ni already happened to diffuse to the middle of pottery and porcelain, si is contained in side of plating Ni layer, explain Si also diffuses to the middle of plating Ni layer. As Ni and Si diffuse, will produce following reaction [2, 3] : This reaction is initiative undertake, earning reacts child is NiSi. Undertake to joint face X diffraction is analysed, the result makes clear, there is the compound between NiSi metal to generate in the interfacial place of pottery and porcelain and film, see a picture 3. The layer shape structure that forms Si3N4/NiSi/Ni and Si3N4/Ni in pottery and porcelain and film interface, and the compound between the metal has bond effect [4, 5] . Diffractive chart of X of interface of graph 3 Si3N4/Ni but from the graph 3 can see, the diffractive peak of NiSi compound is not tall, the setting peak that has Si3N4 of matrix of pottery and porcelain appears, its content is not much it is thus clear that, response is not proper. The NiSi compound layer that in the graph at the same time the interface that Ni of ／ of pottery and porcelain can see in the photograph of 1 is in Bai Liang is very thin, and discontinuous, did not form successive interfacial reaction layer consequently. Can conclude so in connect of drill rod solder, the main union form between pottery and porcelain and plating nickel layer sets band for machinery, but the combinative strength that this interface reacts the layer can improve joint. The intensity of connect of solder of main factor drill rod of intensity of 3 influences connect with magnanimity of experiment stress intensity. Actually, the real strength when contact either place is destroyed should be the result of overlay of experiment stress intensity and stress of this place remains. Of pottery and porcelain and connect of solder of metallic drill rod destroying always is You Mou one local begin. When susceptive of contact some place real stress is more than the real strength of here, cause localized breakdown at here, become the source that whole connect destroys thereby. Because susceptive of contact either place is actual,the vector that stress should be stress of experiment stress and the place remains is mixed, alleviate consequently leftover stress is the important way that increases contact strength; On the other hand, the connect that expects by pottery and porcelain and metal, drill rod these disparate material are formed is in necessarily the different position of contact is existing the vast difference of appearance of composition, organization, substance and property. Different area (or interface) real strength each are not identical, destroy inevitable and initiative at among them the weakest link. Nextpage 　 is more than 1 complex structures as a result of connect of drill rod solder, by each so the intensity of area and 3 join force of the interface decide the intensity of connect of drill rod solder. Ni, Ag-Cu and Q235 area all have enough strength and tenacity, the interface of two place of Ni/Ag-Cu and Ag-Cu/Q235 all belongs to the union between the metal, and metallic key is successive. Si3N4 basically is united in wedlock for covalent bond, hot coefficient of expansion is small, layer of solder of metallic drill rod heats up coefficient of expansion big, in layer of drill rod solder in caky and cooling process, layer of drill rod solder approachs part of pottery and porcelain (include Si3N4/Ni interface inside) will form bigger remains to pull stress, and this kind of stress cannot give through making Si3N4 model changes eliminate; Additional, layer of drill rod solder stands by part of pottery and porcelain to be in from theoretic requirement when transferring to covalent bond by metallic key, should remove certain transition action, however this kind transfers to be put in certain difficulty from theory and practice. Because this can conclude, the area of tall leftover stress of Si3N4/Ni interface and adjacent interface is the most fragile area in connect of drill rod solder. Of this one area rupture intensity is by this the interface of area is reacted a dimension, organization and substance appearance decide, must undertake controlling to affecting the craft standard of afore-mentioned elements consequently, these craft standards have face of pottery and porcelain thick change heat preservation of solder of temperature of solder of ply of degree, film, drill rod, drill rod time, heat speed and cooling rate. In addition, the six to one of hot physics function of pottery and porcelain and metal, there is very great leftover stress in the connect after drill rod solder, reduced the carrying capacity of contact greatly, because this should reduce the leftover stress of contact as far as possible. 3.

1 thick chemical industry art the combinative form between chemical to the influence of contact intensity film and pottery and porcelain is mechanical enchase union, chemical union and sorption, in chemical plating process thick the key that the rate that change is influence union strength. Thick chemical industry art proper, the mechanical and occlusive action of chemical film and place of interface of pottery and porcelain is strong, below temperature of drill rod solder both does not send depart, strength of earning connect union is high. If thick change undesirable, film and place of interface of pottery and porcelain are occlusive action is not strong, in process of subsequently solder of high temperature drill rod, because pottery and porcelain is mixed,the difference of the hot coefficient of expansion of film metal can bring about film local craze, make strength of whole connect union is reduced then. This research is chosen thick the Si3N4 that changes time to be 20 Min and 30 Min undertakes solder of glow drill rod experiments. The experiment makes clear these 2 kinds thick change time to all can obtain figuration the connect of drill rod solder with good compact union. Know by shear test, when film ply is M of 39 μ , si3N4 is thick change shear strength of connect of 20 Min earning to be 56 MPa, si3N4 is thick change shear strength of connect of 30 Min earning to be 78 MPa. Because chemistry is thick,this is change rate the mechanical and occlusive level of different, film and place of interface of pottery and porcelain is different be caused by: Thick change the interface below 30 Min condition to bite collaboration to use apparent prep above thick the interface that changes 20 Min, affect the combinative strength of contact directly so. 3.

The tantalum of impact solid state of intensity of head of butt joint of 2 film ply is 10-5cm2/s amount class about in the diffusion coefficient in fluid photograph, and they are class of amount of 10-8cm2/s ～ 10-9cm2/s only in the diffusion coefficient in solid photograph -- nickel expects in liquid state drill rod diffuse mediumly speed should be compared diffuse mediumly in pottery and porcelain speed is gotten quickly much. If film is too thin (be less than M) of 10 μ , assure to form successive metallic nickel layer in surface of pottery and porcelain hard, improvement of wet to the embellish of surface of pottery and porcelain condition is not big. Dissolve very quickly to makings of liquid state drill rod in layer of Ni of the plating in process of drill rod solder, namely originally discontinuous nickel layer dissolve enters Ag-Cu liquid state in all in brilliant, the mechanical lock union of film and matrix of pottery and porcelain is destroyed, cannot form joint. As the addition of film ply, afore-mentioned circumstances get ameliorative ceaselessly. In process of drill rod solder, the Ni that Ni/Ag-Cu interface stands by in film is participated in deliquescent with diffuse process and dissolve enters Ag-Cu liquid state in all brilliant, the Ni that stands by Si3N4/Ni interface sends out to Si3N4 interface enlarge unripe interface reaction, film is mid still can have delay commentate the action of leftover stress, form successive Si3N4/Ni/Ag-Cu/Q235 multilayer and complex structure, in this kind of complex structure, plating Ni layer and plasticity of brazed seam area are good, can alleviate the leftover stress that pottery and porcelain and Q235 cause because of heating up the vast difference of coefficient of expansion, make the shear strength of whole connect rises thereby. The influence curve of intensity of head of film ply butt joint sees a picture 4, can achieve the deepest film (the shear strength of correspondence of M) of 65 μ is 117.

31MPa. Graph the influence of 4 film ply to contact shear strength 3.

The temperature of solder of influence drill rod of intensity of head of butt joint of temperature of solder of 3 drill rod is one of important parameter of craft of drill rod solder. Raise temperature of drill rod solder, of porcelain of nickel Xiang Tao diffuse speed is accelerated, interfacial reaction aggravate, bond action increases, those who be helpful for contact intensity rise. But of temperature of drill rod solder raise what easier aggravate nickel expects to liquid state drill rod to diffuse, in causing nickel to expect in drill rod dissolve overly, destroy the mechanical lock union between film and pottery and porcelain even, reduce contact intensity thereby. In addition, temperature of drill rod solder is exorbitant, can add the leftover stress of contact, intensity of butt joint head produces adverse effect. Graph the influence curve of intensity of head of butt joint of temperature of the 5 solder that it is drill rod (film ply is M of 39 μ , heat preservation time is 3 Min) , below this condition, intensity of the connect when temperature of drill rod solder is 850 ℃ is highest. Graph the influence of temperature of solder of 5 drill rod to contact shear strength 3.

The influence pottery and porcelain of intensity of head of butt joint of time of heat preservation of solder of 4 drill rod - drill rod solder should abide by the metal to heat equably commonly, the principle of slow refrigeration, below the premise of temperature of solder of affirmatory drill rod, can adjust drill rod solder to heat up a loop through changing time of heat preservation of drill rod solder. Because thermal conductivity of pottery and porcelain is poor, reason extends heat preservation time appropriately, make temperature of pottery and porcelain is changed equably, of the embellish wet spread out that expects to drill rod undoubtedly and leftover stress distributing equably advantageous. But time of heat preservation of drill rod solder is too long, in can having much nickel dissolve to expect into drill rod, should cannot rise to alleviate when film is very thin the action of leftover stress, can reduce contact intensity consequently. Graph the 6 influence curves that are intensity of head of butt joint of time of different heat preservation, in this research, 850 ℃ are in temperature of drill rod solder, film ply falls for the condition of M of 65 μ , the contact intensity that earning of heat preservation 8 Min goes to is highest. Nextpage pursues the influence of time of heat preservation of solder of 6 drill rod to contact shear strength 3.

The delay that the ply of plating Ni layer with 5 intermediate layer certain to the influence of contact intensity ply had leftover stress in contact commentate action, can increase contact shear strength on certain level consequently. But the ply of film is finite, the plating Ni layer with thick M of 65 μ still cannot alleviate adequately in connect of drill rod solder leftover stress, the method gift that accepts intercalary layer only has very good amortize effect. Besides function of connect of influence of function of itself of intermediate layer material, intermediate layer ply also is very big to combining the influence of intensity. This research is condition of 8 Min of time of 850 ℃ , heat preservation to fall in temperature of drill rod solder, the Si3N4 that is M of 28 μ to film ply and Q235 armor plate undertake drill rod solder, layer ply is respectively among Cu 0, 0.

5 Mm and 1 Mm, the value of contact shear strength of place correspondence is 40 MPa, 60 MPa and 112 MPa respectively. Visible, when Cu layer ply is 1 Mm, already can better land alleviates the leftover thermal stress of contact. Pottery and porcelain of 4 plating nickel - the position that fracture surface analysis of the metal ruptures actually according to contact, the cutting of connect of plating nickel Si3N4-Q235 ruptures the form basically has 2 kinds: (1) partial happening produces this kind in pottery and porcelain to rupture in interface, part the intensity that the premise that happen is area of interface of vicinity of pottery and porcelain under pottery and porcelain and intensity of metallic interfacial connection. That is to say, interfacial connection power is very high between metal and pottery and porcelain, but leftover stress exists near the interface. Can see, crackle source is in contact most weak point, namely division of response of interface of pottery and porcelain, along with backward and leftover stress surface layer of bigger pottery and porcelain expands, should bear the weight of sectional and contractible to some limit, criterion contact whole disconnects. Graph the appearance of 7 fracture surface form that rupture for this kind, its are left for material of pottery and porcelain, interfacial area is on the right side of. The graph distributes the × of appearance of fracture surface form that is born in interface, part to happen in pottery and porcelain 7 times 150 　 　 (2) happening expects in Si3N4/Ni interface drill rod with plating Ni the layer reachs drill rod all can obtain between makings and armor plate firm, so this kind ruptures to always happen in the join interface of pottery and porcelain and film, or partial happening is on this interface. It makes clear, the interfacial connection intensity of film and pottery and porcelain is insufficient. A lot of elements can cause this kind to rupture, be like thick change, stuff of chemical plating recipe, film and parameter of craft of drill rod solder (include the atmosphere, time, temperature, ) such as cooling rate. Graph the appearance of 8 form of metallic film surface after rupturing to produce this to plant. Graph the × of 8 appearance of fracture surface form that happen in Si3N4/Ni interface 1505 conclusion 　 (connect of Si3N4-Q235 of nickel of 1) chemistry plating is more than 1 complex structures, destroy often initiative at the weakest link, namely the area of tall leftover stress of interface of pottery and porcelain and adjacent interface. (2) and phase of general method of solder of drill rod of pottery and porcelain are compared, pottery and porcelain of chemical plating Ni undertakes place of drill rod solder needs vacuum to spend inferior. Heating certainly below speed and cooling rate, the main factor that affects contact intensity is as follows: Chemistry is thick temperature of solder of the ply that converts craft, film, drill rod and heat preservation time. Logical choice these standards can be obtained relatively high strenth (117.

31The connect of drill rod solder of MPa) . (Because 3) is chemical the ply of plating Ni layer is finite, was thought to alleviate adequately the leftover stress of contact, cu was inserted in contact intermediate layer. As the addition of intermediate layer ply, contact intensity rises. (The connect of drill rod solder of different union strength has 4) to cut fracture surface feature differently. When pottery and porcelain and power of metallic interfacial connection are high, crackle is initiative at interfacial response division, expand to surface layer of pottery and porcelain subsequently, make brazed seam disconnects finally; If the interfacial connection intensity of film and pottery and porcelain is insufficient, produce whole to disconnect in this interface place. CNC Milling