Brachistochrone-shaped structured solder joint for soldering with heterogeneous materials

Abstract

Brachistochrone-shaped structured solder joint for soldering with heterogeneous materials, characterized in that the solder joint comprises a first solder base material and a second solder base material, wherein the first solder base material has improved wettability with respect to a solder than the second solder base material and brachistochrone-shaped grooves are present on the surface of the second solder base material to be soldered, wherein the brachistochrone-shaped grooves each consist of two brachistochrone-shaped curved surfaces that are arranged symmetrically, and wherein the inner surface curve of the brachistochrone-shaped curved surface corresponds to the brachistochrone equations: x=r(θ-sinθ); y=r(1-cosθ).

Description

Technical FieldThe disclosure relates to the field of material-bonding connection technology, in particular to a brachitrochrome-structured soldered connection for soldering with heterogeneous materials and to the provision method thereof.Background ArtIn the technical field of soldering, heterogeneous materials are usually materials having a great difference in physical or chemical properties, such as modulus of elasticity, coefficient of thermal expansion and melting point, for example ceramic and metal, black metals and non-ferrous metals, copper and stainless steel. Since components made of heterogeneous materials can enable a combination of excellent properties of different materials, the flexibility in terms of structural design is considerably increased, as a result of which the requirements for functionality or performance for modern engineering structures are fulfilled, which gains higher technical or economic meanings and has a broad application possibility in different fields. For this reason, a reliable connection of the heterogeneous materials plays a particularly important role.However, due to the large differences in the physical, chemical, or mechanical properties of heterogeneous materials, metallurgical compatibility during brazing, the formation of brittle joints due to interfacial reactions, and the different coefficients of thermal expansion have a huge impact on the property of the brazing joint during the joining of heterogeneous materials. The problems and difficulties for connecting heterogeneous materials consist primarily in 1 The wettability is quite different when connecting heterogeneous materials and this makes it difficult to wet two types of material simultaneously.A common solder joint consists of a group of substantially parallel surfaces, the solder flowing in a solder joint consisting of two parallel surfaces. Due to the differences in wettability of the solder to two materials and flowability after melting, the solder often does not come into contact with the material on the side difficult to wet and soldering defects are generated, thereby impairing the property of the product.2. Due to the differences in chemical composition of heterogeneous materials, the interfacial reactions are prone to complex interfacial reaction and brittle compounds are excessively generated at the interface.3. The differences in thermal expansion coefficients of heterogeneous materials cause a large residual stress at the interface, and the stress in the brazing joint is difficult to balance, which may cause cracks after brazing.The above-mentioned problems impair the property of the soldered connection. It is of significant importance to provide a solder connection for soldering with heterogeneous materials and their provision methods in order to realize efficient and high-quality soldering.In view of this, the present disclosure is hereby proposed.Subject Matter of the DisclosureIt is an object of the present disclosure to provide a brachitrochrome-structured soldered connection for soldering using heterogeneous materials, with which good soldering quality, reduction of the defects in soldered joints or high strength of the soldered connection can be achieved.The brachitochrome-structured soldered joint for soldering with heterogeneous materials comprises a first soldering base material and a second soldering base material, wherein the first soldering base material has an improved wettability with respect to a solder than the second soldering base material and a brachitochrome-shaped groove is present on the surface of the second soldering base material to be soldered, wherein the brachitochrome-shaped grooves each consist of two brachitochrome-shaped curved surfaces which are arranged symmetrically, and wherein the inner surface curve of the brachitochrome-shaped curved surface corresponds to the Brachitochrome equations: x=r(θ-sinθ); y=r(1-cosθ).A further object of the present disclosure is to provide a method for providing the aforementioned brachitrochrome-structured soldered connection for soldering using heterogeneous materials. The flow rate of the solder on the surface of a material which is difficult to wet, the soldering rate and the homogeneity of the internal stress distribution on the soldered connection are increased by machining a brachistochrone-shaped groove on the surface of the material which is difficult to wet, which reduces the soldering defects in soldering joints and increases the strength of the soldered connection.The method of providing the brachitrochrome-structured soldered connection for soldering with heterogeneous materials comprises the following steps:S1: Machining of Brachistochrone-shaped grooves on the surface to be soldered of a second soldering base material;S 2: soldering with a solder arranged between the surfaces of the first soldering base material and the second soldering base material to be soldered.In contrast to the prior art, the present disclosure has the following advantageous effects:In this disclosure, a brachitrochrome-shaped groove structure is formed on the surface to be soldered of the second brazing base material difficult to wet, whereby the brazing filler metal covers a maximum contact area in a shortest period of time when flowing on the surface of the material difficult to wet, the flow rate of the brazing filler metal on the surface of the material difficult to wet is increased, and brazing defects due to a braze gap clogged by the brazing filler metal are prevented due to an excessively high flow rate of the brazing filler metal on the surface of the material easy to wet. At the same time, the contact area between the material that is difficult to wet and the solder can be increased and the soldering rate on the surface of the material that is difficult to wet can be increased, whereby a high soldering quality of the provided soldered connection for soldering with heterogeneous materials, reduced defects in soldered joints and a high connection strength are achieved.DESCRIPTION OF DRAWINGSIn order to more clearly illustrate technical solutions in specific embodiments of this disclosure or in the related technology, the drawings will be briefly presented below that are necessary in the description of the specific embodiments or the related technology; and naturally, the drawings in the following description show only some embodiments of this disclosure, and other drawings may be available to those skilled in the art with reference to these drawings without expending inventive activity. FIG. 1 is a schematic diagram of a first interface structure between the first and second solder base materials of the present disclosure; FIG. 2 is a schematic diagram of a second interface structure between the first and second solder base materials of the present disclosure; FIG. 3 is a schematic diagram of a third interface structure between the first and second solder base materials of the present disclosure; FIG. 4 is a schematic structural diagram of the surface to be soldered of the second base material in an embodiment of the present disclosure; FIG. 5 is a schematic structural diagram of the mesh pattern on the surface to be soldered of the first base material in an embodiment of the present disclosure; FIG. 6 is a schematic diagram of an interface structure between the first and second materials in an embodiment of the present disclosure; FIG. 7 is a schematic diagram of an interface structure between the first and second materials in another embodiment of the present disclosure; FIG. 8 is a schematic illustration of the joined interface of a solder joint in an embodiment of the present disclosureReference Number:1 - first solder base material; 11 - grid pattern; 12 - brachitochrome ridge; 13 - easy-to-wet surface; 14 - to-be-soldered surface - YG8; 15 - TC4; 2 - second solder base material; 21 - brachitochrome-shaped groove; 211 - receiving groove; 212 - brachitochrome; 22 - hard-to-wet surface; 23 - to-be-soldered surface - PCBN; 24 - Al 2 O 3; 3 - solder; 4 - copper; 5 - stainless steel.Detailed Description of EmbodimentsHereinafter, technical solutions of this disclosure will be clearly and fully described with reference to terms and specific embodiments. However, it should be understood by those skilled in the art that the described embodiments are only partial embodiments, rather than all of the embodiments of this disclosure, which are provided merely to illustrate the present disclosure and are not to be considered as limiting to the claimed scope of the present disclosure. All other embodiments that would be available without inventive activity by the person skilled in the art based on the exemplary embodiments in the present disclosure fall within the scope of protection of this disclosure. In the embodiments, unless otherwise indicated, they are conventional or manufacturer recommended conditions. Unless the manufacturer is stated, the reagents or instruments used are conventional products which are commercially available.As shown in FIGS. 1, 2, and 3, the first aspect of this disclosure provides a brachitrochrome-shaped structured brazing joint for brazing with heterogeneous materials, comprising a first brazing base material 1 and a second brazing base material 2, wherein the first brazing base material 1 has improved wettability to a brazing than the second brazing base material 2, and a brachitrochrome-shaped groove 21 is provided on the surface to be brazed of the second brazing base material 2, wherein the brachitrochrome-shaped grooves 21 are each composed of two brachitrochrome-shaped curved surfaces arranged symmetrically, and wherein the inner surface curve of the brachitrochrome-shaped curved surface satisfies the brachitrochrome equations: x=r(θ-sinθ); y=r(1-cosθ).As shown in FIG. 1, the inner surface curve of the brachitochroone curved surface is the intersection curve between the plane perpendicular to the surface to be soldered of the second brazing base material 2 and the extending direction of the brachitochroone shaped groove 21 and the brachitochroone shaped groove 21.The term "brachistochroone" is a curve along which a mass point slides most rapidly from a stationary point A to a stationary point B in a perpendicular plane, the point A being not lower than the point B. The mass point is only under the influence of the gravitational force and starts at zero speed. For a solder joint, a "brachistochroone" is present when alloy droplets of molten solid solder move along a solder joint from one point to another point. The brachistochrons can be represented in the form of the parameter equations as x=r(θ-sin θ); y=r(1-cos θ), where r and θ depend on the location of the end point. Thus, a group of the "brachistochrons" is present for any two points that are under a single force without an initial velocity.A common solder joint consists of a group of substantially parallel surfaces, the solder flowing in a solder joint consisting of two parallel surfaces. However, due to the differences in wettability of the solder to two materials and flowability or viscosity after melting, when bonded to heterogeneous materials, the solder often fails to come into contact with the material on the side difficult to wet and soldering defects are generated, thereby impairing the property of the product.In this disclosure, in order to increase wettability of the solder on the surface of the hard-to-wet material, improve homogeneity of residual stress at the solder joint, and prevent cracks due to concentrated stress, the flow rate of the solder in solder joints is controlled by forming a Brachitrochrome-shaped groove structure on the soldering surface of the hard-to-wet second solder base material. The formation of the brachitochrone-shaped structure on the surface of the hard-to-wet material allows the solder to cover a maximum contact area in a shortest period of time when flowing on the surface of the hard-to-wet material, increases the flow rate on the surface of the hard-to-wet material, and avoids solder defects due to the solder joints clogged by the solder covering the solder joints due to an excessively high flow rate of the solder on the surface of the easily-to-wet material. At the same time, the contact area between the material that is difficult to wet and the solder can be increased and the soldering rate on the surface of the material that is difficult to wet can be increased, whereby the properties of the soldered connection for soldering with heterogeneous materials are improved.The brazing joint for brazing with heterogeneous materials provided by this disclosure has advantages such as good brazing quality, reduction of defects in brazing joints, and high joining strength, respectively, and is relevant to the application of the components made of heterogeneous materials.As shown in FIG. 4, in some specific embodiments of the present disclosure, the surface to be soldered of the second brazing base material 2 is provided with some brachistochrome-shaped grooves 21 arranged in parallel. It is possible to reduce the consumption of solder with a constant contact area between the solder and the material which is difficult to wet by increasing the number of brachitrochrome-shaped grooves 21 with a constant total length of the solder joint.In some preferred embodiments, the some brachistochroone-shaped grooves 21 are uniformly distributed on the surface to be soldered of the second solder base material 2 to increase homogeneity of the solder and stress distribution.In some specific embodiments of the present disclosure, the vertical distance H and the horizontal distance L between the start point and the end point of the brachitochroones in the inner surface of the brachitochroone-shaped groove 21 and the size d of the solder particles agglomerated when the solder used melts correspond to the following relationships: H≥8d, L≥8d.With the starting point as the starting point, the position of the end point and thus the values of r and θ can be determined on the basis of the vertical distance H and the horizontal distance L between the starting point and the end point of the brachistochroone. The joining strength of the brazing joint can be increased by making the vertical distance H and the horizontal distance L not smaller than 8 times the size of the agglomerated particles when the brazing filler metal melts. If the brachistochroone-shaped grooves 21 are too small, the effect of improving the joint strength is not seen. However, it would not be ever more preferable if the brachistochroone-shaped grooves are larger, since the consumption of the solder and thus the cost increase with an excessive dimension of the brachistochroone-shaped grooves 21. In some preferred embodiments of the present disclosure, the vertical distance H and the horizontal distance L are in a range of 8 d≤H≤15 dand 8 d≤L≤15 din which the solder connection has satisfactory performance and no waste of the solder occurs.In some specific embodiments of the present disclosure, the surface to be soldered of the first solder base material 1 is provided with a grid pattern 11.Alternatively, the surface of the first base material 1 to be soldered is provided with brachitrochrome-shaped protrusions 12, the brachitrochrome-shaped protrusions 12 fitting to the brachitrochrome-shaped grooves 21 and forming a structure engageable with these protrusions.Thus, in some embodiments of the present disclosure, the interface of the brazing joint for brazing with heterogeneous materials may be geometrically designed such that the surface to be brazed of the first brazing base material 1 is an unprocessed smooth surface and the surface to be brazed of the second brazing base material 2 is provided with brachitrochrome-shaped grooves 21 (as shown in FIG. 3 ), or that the surface to be brazed of the first brazing base material 1 is provided with the grid pattern 11 and the surface to be brazed of the second brazing base material 2 is provided with brachitrochrome-shaped grooves 21 (as shown in FIG. 1 ), or that the surface to be soldered of the second brazing base material 2 is provided with brachistochrome-shaped grooves 21 and the surface to be soldered of the first brazing base material 1 is provided with brachistochrome-shaped protrusions 12 forming a structure engageable with the brachistochrome-shaped grooves 21 (FIG. 2 ).As shown in FIG. 5, in some specific embodiments of the present disclosure, the lattice pattern 11 on the surface of the first brazing base material 1 is composed of longitudinally and transversely crossed grooves.When the surface to be soldered of the first brazing base material 1 is provided with a mesh pattern 11, the flow rate of the solder on the surface of the easily wetted material can be reduced with inhibiting action of the mesh pattern 11, and the flow rate of the solder on the surface of the hard to be wetted surface can be increased by means of the brachistochrone-shaped grooves 21. The two cooperate with each other so that the solder covers the two surfaces to be soldered simultaneously and soldering errors are reduced. Further, the grooves in the mesh pattern can receive the excessive solder, and the mesh pattern can increase the roughness of the surface of the material, thereby increasing the adhesion force of the surface to the solder and the contact area of the solder with the material.When the surface to be soldered of the first brazing base material 1 is provided with brachitrochrome-shaped protrusions 12 forming a structure engageable with the brachitrochrome-shaped grooves 21, the brachitrochrome-shaped structure is concaved on the surface of the material difficult to wet, increasing the wetting angle, and the brachitrochrome-shaped structure is convexed on the surface of the material easy to wet, reducing the wetting angle. With such a structure, a uniform flow channel for the solder is formed at the brazing joint, thereby spontaneously discharging gases, remarkably reducing leakage, properly disposing contaminants outside the brazing joints, and bond strength can be increased. Further, this structure can reduce consumption of the solder, shorten the time of soldering, and increase the soldering efficiency as compared with a smooth surface or a grid pattern on the surface of the easily wetted material.In some specific embodiments of the present disclosure, the structures on the surface of the first solder base 1 and the second solder base 2 are geometrically designed to be micron.In some specific embodiments of the present disclosure, a receiving groove 211 is provided at the transition between two symmetrically arranged brachistochroone-shaped curved surfaces within a brachistochroone-shaped groove 21 configured to receive the excess solder. At the same time, the contact area between the material and the solder is increased and the connection strength is increased. The receiving groove 211 has a depth of ≥r / 5 and a width of ≥r / 5.If the receiving groove 211 is too small, the improvement in shear strength is not seen, if it is too large, it results in a large consumption of the solder, a long time of soldering, a low soldering efficiency, and a high cost. In some preferred embodiments of the present disclosure, the receiving groove 211 has a depth of r / 5-3r such as r / 5, r / 4, r / 2, r, 2r, and 3r, and a width of r / 5-3r such as r / 5, r / 4, r / 2, r, 2r, and 3r.In some specific embodiments of the present disclosure, edges in the surface structure of the surface to be soldered of the second brazing base material 2 are all rounded so that the brazing material smoothly flows. The distribution of residual stress due to brazing can be homogeneous by forming various curved (brachistochrone-shaped grooves) and arcuate structures on the surface, thereby preventing cracks due to concentrated stress.In some specific embodiments, the first solder base material 1 is one of YG8 and TC4, and / or the second solder base material 2 comprises one of PCBN and alumina ceramic.In some specific embodiments of this disclosure, the first solder base material 1 is YG8 and the second solder base material 2 is PCBN.In some other embodiments of this disclosure, the first brazing base material 1 is TC4 and the second brazing base material 2 is an alumina ceramic.In a second aspect of the present disclosure, a method for providing the brachitrochrome-structured soldered connection for soldering with heterogeneous materials according to one of the preceding embodiments is provided, comprising the following steps:S1: Machining of Brachistochrone-shaped grooves on the surface to be soldered of a second soldering base material;S 2: soldering with a solder arranged between the surfaces of the first soldering base material and the second soldering base material to be soldered.In the method of this disclosure, brachitrochrome-shaped grooves are formed on the surface to be soldered of the second brazing base material that is difficult to wet, so that the flow rate of the brazing material on the surface of the material that is difficult to wet is increased, defects due to an excessively high flow rate of the brazing material on the surface of the material that is easy to wet are avoided, the contact area between the material that is difficult to wet and the brazing material is increased, and the brazing rate on the surface of the material is increased. The method can significantly improve the soldering quality of the soldered connection for soldering with heterogeneous materials and increase the connection strength.In some specific embodiments of the present disclosure, the step S 1 further includes a step of forming a grid pattern or brachistochrome-shaped protrusions on the surface of the first brazing base material to be soldered.By working out the mesh pattern on the surface to be soldered of the first brazing base material, it is possible to reduce the flow rate of the solder on the surface of the easily wetted material, to reduce the differences in the speed of the solder on the surface of the two materials, so that the solder covers the two materials at the same time, to reduce defects in brazing seams, to simultaneously increase the contact area between the solder and the brazing base material, and the roughness of the brazing base material, thereby increasing the brazing rate and the joining strength.By working the brachistochroone-shaped protrusions forming a structure engageable with the brachistochroone-shaped grooves on the surface to be soldered of the first solder base material, it is also possible to increase the joining strength. On the other hand, although the mesh pattern is preferable from the viewpoint of improving the connection strength, the brachistochroone-shaped protrusions may reduce consumption of the solder as compared with the mesh pattern, thereby shortening the time of soldering and increasing the soldering efficiency.In some specific embodiments of this disclosure, the process for processing the first and second solder base materials in step S 1 includes WEDM-LS and / or short pulse laser methods.In some specific embodiments of this disclosure, further steps are provided for pretreating the surface to be soldered of the first and second brazing base materials prior to step S 1, wherein the pretreatment comprises sandblasting and / or polishing the surface to be soldered with a sandpaper, supersonic cleaning, and drying.In some specific embodiments of this disclosure, supersonic cleaning is performed in acetone with a duration of 10-20 min, such as any score of 10 min, 12 min, 14 min, 15 min, 16 min, 18 min, and 20 min, or a range of values between any two scores centered.In some specific embodiments of this disclosure, the soldering method includes vacuum soldering and / or inductive soldering.In some specific embodiments of this disclosure, the first solder base is YG8and the second solder base is PCBN, wherein the solder is CuSnTi, the soldering temperature is 800-1000° C., such as any point value of 800° C., 850° C., 900° C., 950° C., 1000° C., or a range of values between any two points, the heating rate is 1-20° C. / min, such as any point value of 1° C. / min, 3° C. / min, 5° C. / min, 10° C. / min, 12° C. / min, 14° C. / min, 16° C. / min, 18° C. / min, 20° C. / min, or a range of values between any two points, mid.In some specific embodiments of this disclosure, the first brazing base material is TC4 and the second brazing base material is an alumina ceramic, wherein the brazing material is TiZrCuNi, the brazing temperature is 950-1000° C., such as any score of 950° C., 980° C., 1000° C., or a range of values between any two scores therebetween, the heating rate is 1-20° C. / min, such as any score of 1° C. / min, 3° C. / min, 5° C. / min, 10° C. / min, 12° C. / min, 14° C. / min, 16° C. / min, 18° C. / min, 20° C. / min, or a range of values between any two scores centered.The embodiments of the present disclosure will be explained in detail below with reference to a specific exemplary embodiment. The starting materials used in the embodiment are all commercially available unless otherwise indicated.In one possible implementation, a WEDM-LS geometric shape fabrication machine according to this disclosure is used on a PCBN / YG8 lötverbindung joint, where the interface structure is as shown in FIG. 6 and CuSnTi is used as the solder.Step 11: Pretreating the surface to be soldered of PCBN and YG8 by sandblasting the surface to be soldered of the material to be soldered, subsequently supersonically cleaned in acetone for 15 min, and finally naturally dried.Step 12: Process the surface of PCBN to be soldered using a WEDM-LS machine and introduce the Brachistochrone equations according to this disclosure into CAD software. Reference is made to documents that the commercially available solder CuSnTi has a size of the agglomerated particles of approximately 2-3 μm during melting of the solder. It is assumed that θ at the starting point is 0° and θ at the ending point is 120°, and r is 20 μm, the vertical distance between the starting point and the ending point is 30 μm, and the horizontal distance therebetween is 25 μm. In the region of these brachistochroones, the particle which is formed during the agglomeration of the solder can be regarded as a mass point. The two brachistochroone-shaped curved surfaces are connected by means of a receiving groove which has a depth of 20 μm and a width of 20 μm. The machining is automatically performed by the apparatus according to a CAD drawing and programs.Step 13: Machining the surface to be soldered of YG8 by means of a WEDM-LS machine, wherein grooves 20 μm deep and 20 μm wide are first cut transversely at a distance of 20 μm and then the YG8 sample is rotated through 90° and grooves 20 μm deep and 20 μm wide are cut longitudinally at a distance of 20 μm in order to form a grid pattern.Step 14: Coating the solder CuSnTi between the surfaces to be soldered of the two materials to be soldered beforehand, heating in a furnace for vacuum soldering under a degree of vacuum of 1×10 -3 Pa and a heating speed of 10° C. / min up to 900° C., cooling under a cooling speed of 10° C. / min up to 400° C. subsequent to a heat hold for 2 min and then natural cooling in the furnace to obtain the soldered connection.Step 15: Determine the shear strength of the prepared brazing joint with a universal mechanical testing machine after completion of the brazing, the results showing that the brazing joint prepared in this embodiment has a shear strength of 269 MPa.Optionally, and in contrast to the above embodiment, it is also possible not to perform any additional processing of the surfaces of PCBN and YG8 to be soldered, i.e. the method comprises only steps 11, 14 and 15 in the above implementation. The determination of the connection after the soldering shows a shear strength of 147 MPa. Thus, the strength with steps 11 to 15 is increased by 83% than the strength with only steps 11, 14 and 15.In some embodiments and in contrast to steps 11-15 above, a short pulse laser is used for machining the surface to be soldered of PCBN to achieve a more accurate manufacturing measure, wherein the process size comprises a laser power of 300 W, a frequency of 1000 Khz, a scanning speed of 40 mm / s, and the machined receiving groove is 4 μm deep and 4 μm wide. At this time, the brazing joint has a strength of 207MPa which increases 41% as compared with that of Steps 11, 14 and 15 and decreases 23% as compared with that of Steps 11-15, the optimum time of brazing is 2min which remains unchanged as compared with that of Steps 11-15, and the consumption of the brazing filler reduces 10% as compared with that of Steps 11-15.In some embodiments and in contrast to steps 11- 15, the recessed receiving groove is 60 μm deep and 60 μm wide. In this case, the soldered joint has a strength of 298 MPa which increases by 10.8% compared with that of steps 11-15, but the time of soldering reaches 4 m and is extended by 100% and the consumption of the solder increases by 82%.In another possible implementation, a pulse laser or a WEDM-LS machine is used to produce the geometric shape according to this disclosure in a soldered connection Al 2 O 3 and TC4, wherein the interface structure is as shown in FIG. 7 and a commercially available solder TiZrCuNi is used for soldering.Step 21: Pretreatment of the surfaces to be soldered of aluminum oxide ceramic and TC4 titanium alloy, wherein the surfaces to be soldered of the materials to be soldered are polished by means of a sand paper and supersonically cleaned in acetone for 15 min and finally naturally dried.Step 22: Cutting the surfaces to be soldered of Al 2 O 3 or. TC4 with the pulse laser or WEDM-LS machine and introducing the Brachistochrone equations according to this disclosure into CAD software. It is assumed that the angle θ is 0° at the starting point and 180° at the ending point, and r is 30 μm. Between the starting point and the end point of the brachistochrons, a vertical distance of 60 μm and a horizontal distance of 94.25 μm are thereby produced. After the generation of the left brachitochromes, the right brachitochrome is generated mirror-symmetrically, wherein the distance between all two closed brachitochromes is 30 μm. A convex region is worked out on the side of the material TC4 which is easy to wet, and a concave region on the side Al 2 O 3 wherein the working takes place automatically by the device according to a CAD drawing and programs.Step 23: Coating the solder TiZrCuNi between the surfaces to be soldered of the two materials to be soldered beforehand, heating in a furnace for vacuum soldering under a degree of vacuum of 1×10 -3 Pa and a heating rate of 10° C. / min up to 950° C., cooling under a cooling rate of 10° C. / min up to 300° C. subsequent to a heat hold for 15 min, and then naturally cooling in the furnace to obtain the soldered connection.Step 24: Determination of the shear strength of the produced soldered connection by means of a mechanical universal testing machine, wherein the results show that the soldered connection produced in this exemplary embodiment has a shear strength of 60 MPa, which increases by 50% compared to a soldered connection not treated in this way.Optionally, and in contrast to the above embodiment, it is also possible not to perform any additional processing of the surfaces of Al 2 O 3 and TC4 to be soldered, i.e. the method comprises only steps 21, 23 and 24 in the above implementation. The determination of the connection after the soldering shows a shear strength of 40 MPa.In some embodiments and in contrast to steps 11-15, the interface of the solder joint is formed as shown in FIG. 3, wherein the surface to be soldered of YG8 is left unprocessed and brachitrochrome-shaped grooves are formed on the surface to be soldered of PCBN and the remaining parameters remain unchanged compared to steps 11-15. The soldered connection produced has a shear strength of 173 MPa, which increases by 17.7% compared to that with steps 11, 14 and 15 and reduces by 35.7% compared to that with steps 11-15. In some embodiments and in contrast to steps 11-15, the interface of the solder connection is as shown in Fig. 2. Brachitrochrome-shaped ridges are machined on the surface to be soldered of YG8, and brachitrochrome-shaped grooves are machined on the surface to be soldered of PCBN, with the remaining parameters remaining unchanged compared to steps 11-15. The soldered connection produced has a shear strength of 192 MPa, which increases by 30.6% compared with that in steps 11, 14 and 15 and reduces by 28.6% compared with that in steps 11-15. However, the soldering time is 1 min, i.e. the speed increases 100% compared with that of steps 11-15, and the consumption of the solder is saved 72% compared with steps 11-15.In some embodiments and in contrast to the last embodiment, a receiving groove of 20 μm×20 μm is additionally worked out in the brachistochroone-shaped groove on the surface of PCBN to be soldered, wherein the remaining parameters remain unchanged than in the last embodiment. The soldered connection produced has a shear strength of 213 MPa, which increases by 11% compared to the last exemplary embodiment. The soldering time is 1.2 min, which extends by 20% compared to the last exemplary embodiment, and the consumption of the solder increases by 14% compared to the last exemplary embodiment.In some embodiments and in contrast to steps 11-15, no receiving groove is formed in the brachitrochrome shaped groove on the surface of PCBN to be soldered, the remaining parameters remaining unchanged than in steps 11-15. The soldered connection produced has a shear strength of 247 MPa, which is reduced by 8% compared to steps 11- 15. The soldering time is 1.6 min, which is shortened by 20% compared with steps 11-15, and the consumption of the solder is reduced by 20% compared with steps 11-15,In another possible embodiment, a CNC machine is used to produce the geometric shape according to this disclosure on the end face of a stainless steel tube having an inner diameter of 30 mm and a tube thickness of 6 mm and a copper tube having a tube thickness of 5 mm. Soldering is performed with inductive heating, as shown in FIG. 8.Step 31: Determining the dimensions of the brachistochroones as a function of the tube thickness 5 mm of the copper tube. It is assumed that the angle θ at the start point is 0° and at the end point is 180°, and r is 1.5 mm, the horizontal distance between the start point and the end point of the Brachistochrone curve is 4.71 mm, and the vertical distance therebetween is 3 mm.Step 32: Rotating a concave curved surface having the Brachistochrone curve determined in Step 31 toward the inner bore from a point on the outer diameter of the stainless steel pipe by means of a CNC machine, and rotating a horizontal platform from the end point of the curve toward the inner bore.Step 33: Rotate a convex curved surface having the Brachistochroone curve determined in Step 31 toward the outer periphery from a point on the outer diameter of the copper pipe by a CNC machine, and rotate a horizontal platform toward the inner bore.Step 34: Set the stainless steel pipe down with the concave curved surface upward and the copper pipe with the convex curved surface downward to join the two pipes together. Ring-shaped silver filler wires (trade name: ZRIME, trade name: Ag25CuZn) are inserted into the joint.Step 35: heating the two tubes in step 34 in an inductive heating coil by means of a high-frequency heating device under a heating power of 20 KW, it being possible to see that the solder flows out of the interior of the soldered seam at a heating time of 4 s, with the result that the soldering is completed at this point in time.Optionally, and in contrast to the above embodiment, the surfaces joined in the brazing joint at the end face of the stainless steel pipe and the copper pipe are smooth, with the remaining conditions remaining unchanged as in Embodiment 9. the time of brazing is 7s which is elongated by 75% compared to Steps 11-15, and the brachitrochrome-shaped structured brazing joint can significantly shorten the time of brazing and increase the brazing efficiency.Although this disclosure is illustrated in detail with reference to the foregoing respective embodiments, it should be noted that the above respective embodiments are only for illustrating the technical solutions of this disclosure, rather than limiting the same. Those skilled in the art should understand that the technical solutions recorded in the foregoing respective embodiments could be further modified or partial or all technical features could be equivalently substituted therein as long as it does not depart from the spirit and scope of this disclosure. However, these modifications or substitutions do not cause a departure from the spirit and scope of this disclosure. Therefore, it is intended that the appended claims cover all such substitutions and modifications within the scope of the present disclosure.Commercial utilityUsing the above-described technical solutions, a brachistochrone-shaped groove structure is formed on the soldering surface of the second soldering base material that is difficult to wet, whereby the solder covers a maximum contact area in a shortest period of time when flowing on the surface of the material that is difficult to wet, the flow rate of the solder on the surface of the material that is difficult to wet is increased, and defects due to a solder gap clogged by the solder due to an excessively high flow rate of the solder on the surface of the material that is easy to wet are avoided. At the same time, the contact area between the material that is difficult to wet and the solder can be increased and the soldering rate on the surface of the material that is difficult to wet can be increased, whereby a high soldering quality of the provided soldered connection for soldering with heterogeneous materials, reduced defects in soldered joints and a high connection strength are achieved.In summary, the disclosure relates to the field of material-bonding connection technology, in particular to a brachitrochrome-shaped structured soldered connection for soldering with heterogeneous materials and their provision methods. The brachitrochrome-shaped structured brazing joint for brazing with heterogeneous materials comprises a first brazing base material and a second brazing base material, wherein the first brazing base material has an improved wettability with respect to a brazing material than the second brazing base material and brachitrochrome-shaped grooves are provided on the surface of the second brazing base material to be brazed, wherein the brachitrochrome-shaped grooves each consist of two brachitrochrome-shaped curved surfaces which are arranged symmetrically, and wherein the inner surface curve of the brachitrochrome-shaped curved surface corresponds to the brachitrochrome equations. Its provision method comprises the following steps: S 1, machining of brachitrochrome-shaped grooves on the surface to be soldered of a second soldering base material; S 2, soldering with a solder arranged between the surfaces to be soldered of the first soldering base material and of the second soldering base material. The brachitrochrome-structured soldered connection provided in this disclosure for soldering with heterogeneous materials has good soldering quality and reduced defects in soldered joints, whereby the shear strength of the soldered connection can be significantly increased

Claims

A brachitochrome-structured brazing joint for brazing with heterogeneous materials, characterized in that the brazing joint comprises a first brazing base material and a second brazing base material, wherein the first brazing base material has an improved wettability with respect to a brazing material than the second brazing base material and brachitochrome-shaped grooves are provided on the surface of the second brazing base material to be brazed, wherein the brachitochrome-shaped grooves are each composed of two brachitochrome-shaped curved surfaces arranged symmetrically, and wherein the inner surface curve of the brachitochrome-shaped curved surface corresponds to the brachitochrome equations: x=r(θ-sinθ); y=r(1-cosθ).A brachitrochrome-shaped structured soldered connection for soldering with heterogeneous materials according to claim 1, characterized in that the surface of the second soldering base material to be soldered is provided with a plurality of brachitrochrome-shaped grooves arranged in parallel.The brachitochrome-shaped structured brazing joint for brazing with heterogeneous materials according to claim 2, characterized in that the plurality of brachitochrome-shaped grooves are evenly distributed on the surface to be brazed of the second brazing base material.The brachitrochrome-shaped structured brazing joint for brazing with heterogeneous materials according to claim 1, characterized in that the vertical distance H and the horizontal distance L between the starting point and the ending point of a brachitrochrome in the inner surface of the brachitrochrome-shaped groove and the size d of the brazing particles agglomerated when the brazing material used melts correspond to the following relationships: H≥8d, L≥8d.The brachitochrone-shaped structured brazing joint for brazing with heterogeneous materials according to claim 1, characterized in that the surface to be brazed of the first brazing base material is provided with a grid pattern, or that the surface to be brazed of the first brazing base material is provided with brachitochrone-shaped ridges which can fit the brachitochrone-shaped grooves and form a structure engageable with the brachitochrone-shaped grooves.A brachitrochrome-shaped structured brazing joint for brazing with heterogeneous materials according to claim 5, characterized in that the grid pattern on the surface of the first brazing base material consists of transversely and longitudinally crossed grooves.Brachitrochrome-shaped structured solder connection for soldering with heterogeneous materials according to one of claims 1 to 6, characterized in that the solder connection comprises at least one of the following features: a. a receiving groove is present at the transition between two symmetrically arranged brachitrochrome-shaped curved surfaces within the brachitrochrome-shaped grooves, wherein the receiving groove has a depth of ≥r / 5 and a width of ≥r / 5; b. edges or corners in the surface structure of the surface to be soldered of the second solder base material are all rounded.The brachitrochrome structured solder joint for soldering with heterogeneous materials according to any one of claims 1 to 7, characterized in that the first solder base material is one of YG8 and TC4; and / or that the second solder base material comprises one of PCBN and alumina ceramic.

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