Method for laser fusion using ablation coating. RU patent 2520252.
 Workpiece with surface pre-treated prior to sputtering, pre-treatment method of workpiece surface prior to sputtering and pre-treatment device of workpiece surface prior to sputtering / 2500832Workpiece with treated surface includes parts in the form of grooves and parts in the form of flanges, which are formed in turn on the workpiece surface. Besides, the workpiece has uneven surfaces formed on tops of parts in the form of flanges and small-roughness sections being smaller than uneven surfaces and formed by treatment on parts in the form of grooves among alternatively formed parts in the form of flanges and parts in the form of grooves. |
 Method of reforming metal parts / 2498888Invention relates to reforming of metal parts jointed by high-temperature soldering. Soldered zones are reformed with the help of laser. Laser peak power makes 1500-3000 W. Laser is operated in pulse mode at pulse frequency of 4-8 Hz. |
 Plant for making parts by layer-by-layer synthesis / 2487779Invention relates to powder metallurgy, particularly, to materials intended for production of parts by layer-by-layer synthesis. It may be used in various branches of machine industry. Proposed plant comprises worktable, desk for fritting, mechanism to feed powder onto worktable, device to collect excess powder and powder layers levelling device including carriage with blade displace by drive above worktable surface. Said carriage represents a rectangular structural part with L-like brackets secured to its ends and arranged in two parallel slots made in worktable edges and levelling blade case arranged at its front edge. Sliders are arranged at L-like brackets ends, on guides secured to worktable bottom surface. Worktable is equipped with slot protective devices. |
 Method and apparatus for laser treatment of glass-ceramic surface / 2485064Invention relates to treating the surface of ceramic materials with laser radiation to obtain nanostructured amorphised films, mainly from glass-ceramic. The method can be used for surface finishing of components used in electronic engineering. The method for laser treatment of glass-ceramic surface involves laser irradiation of a glass-ceramic plate with preheating and subsequent step-by-step cooling. The glass-ceramic plate is placed in a closed volume made from heat-insulating material and laser irradiation is carried out through an optical filter which transmits radiation in the spectral range of the wavelength of the working laser and blocks radiation in the infrared range. The apparatus for laser treatment of glass-ceramic surface which has a CO2 laser, an optical system with a focusing lens for scanning a beam on the surface of the sample, a control computer, a working table with a heater and a sample, which is equipped with means of protecting and cooling the focusing lens from thermal action. The apparatus is equipped with a chamber made from heat-insulation material in which there is a heater with a sample, wherein between the chamber and the focusing lens there is an optical filter which closes the sample in a closed volume, which transmits radiation of the working laser and blocks radiation in the infrared range. |
 Ion implantation method of surfaces of parts from structural steel / 2482218Method involves implantation into the steel surface of copper ions, and then lead ions. Prior to the implantation, the part surface shall be treated with a laser beam that is focused at the spot in the form of a circle with specific emission density of 260-800 W/mm2; after that, the spot is moved along the treated surface at the speed of 25-40 mm/s. |
 Method of sizing metals and alloys / 2451582Proposed method intended for sizing hard-to-machine metals and alloys and may be used in sizing current conducting parts. Electrochemical dissolution is effected in machining zone subjected to laser radiation. Laser radiation effects are formed in wavelength range comprises, at least, one wavelength in IR spectrum and, at least, one wavelength in UV spectrum. Laser radiation density and exposure of machined surface to said radiation are defined subject to thermal characteristics of machined material, electrolyte boiling point and initial temperature. |
 Method of part sintering by laser layer-by-layer synthesis / 2450891Invention relates to powder metallurgy, particularly, to selective laser sintering of 3D articles. It may be used for making complex-shape parts for machine building. Powder layer trial tracks are pre-sintered by sets of combinations of process parameters including radiant power and rate of displacement of minimum-focus laser beam and that of defocused maximum-diameter beam for given conditions of sintering. Digital shooting of sintered trial tracks is carried out to process obtained shots to select optimum sintering conditions by selecting tracks by their maximum width and to sinter every layer of processed part at optimum processing parameters. In every layer sintered are lines of contour 3 by minimum-focus laser beam with maximum gap 4 between first and second points closed by laser beam part equal to Z=0.5×(H-B), where Z is said gap between first and last points 5, 6; H is width of sintered track; B is track overlap. Sintering of cells areas is carried out by defocused laser beam with overlap of tracks 9 equal to B=(0.05-0.1)H. With laser beam approaching part contour, beam direction is selected to provide for angle between beam travel vector and tangential vector at crossing with part contour makes π/4≤β≤π/2. |
 Method of laser electroslag welding / 2447980Proposed method relates to hydride method of laser welding, particularly, to laser electroslag welding to be used in machine building for producing welded structures at larger thickness of welded edges. Slag and metal baths are formed. Said baths are retained in space limited by copper shaping plates and weld seam edges. Slag, filler wire or consumable plate electrode, seam metal or edges are heated by heat released by electric current passing between electrodes and seam metal and through fused slag. Laser beam is fed onto slag bath surface, its power being uniformly distributed over welding bath mirror surface and filler wire of consumable electrode feed rate being simultaneously increased. |
 Method for obtaining wear-resistant surface of metals and their alloys (versions) / 2445378According to the first version, the method involves formation of near-surface laser plasma in metal vapours in continuous optical discharge. Near-surface plasma is formed at least with one alloy element or elements; power density of laser radiation Wp is determined from the following condition: where - power density of laser radiation, which leads to surface melt, - power density of laser radiation, which leads to formation of erosion plasma and destruction of the surface, and together with laser plasma the treated surface is treated with ultrasound. According to the second version, the surface is treated with ultrasound in addition to laser plasma. Either carbon or nitrogen or boron or chrome is used as alloy element or elements. |
| Method of producing diamond drilling tool / 2432229 Invention relates to powder metallurgy, particularly, to method of fabrication of diamond drilling tool comprising stem with working layer and axial coolant passage bore. Proposed method comprises moulding and heat treating of mix material arranged in mould and containing diamond powder and metal binder powder, and making bore in working layer. Note here that working layer is briquetted and welded to stem. Coolant bore is drilled by laser or electric spark. |
 Monocrystalline welding of materials hardened in one direction / 2516021Invention relates to laser surfacing of metal hardened in one direction. Powder is fed onto substrate surface (4) of structural element (1, 120, 130) made of hardened metal with dendrites (31) oriented in one direction (32). Beam scanning rate, laser power, beam diameter, powder stream focus and/or powder flow rate are set to ensure local orientation of temperature gradient (28) at crystallisation front (19) less than 45° towards substrate dendrite direction (32) for dendrite (31) in substrate (4). |
| Method of surface processing / 2514233 Invention relates to steel surface processing. Steel surface is cleaned of scale and processed by laser beam. Surface laser processing is executed by pulse laser radiation with wavelength of 0.8-1.2 mcm, power of 105-107 W/cm2, pulse frequency of 28-35 kHz and surface scanning rate of 8-12 cm/s. To form iron oxide layer on steel surface to preserve composition and properties of deeper metal plies, laser processing is performed to depth of 10-40 nm. |
 Method of welding the billets of high-refractory super alloys at definite filler material feed weight rate / 2510994Invention relates to laser welding of billets (9) from high-refractory super alloys. Heat laser source (3) creates generates zones (11) of heat feed to billet surface (10). Welding filler (13) is fed by device (5) to heat feed zone (11) and driven by transfer device (15) between heat source (3) and feed device (5) on one side and, on opposite side, and billet surface (10). Welding filler is fed at weight rate ≤350 mg/min. |
 Method of reconditioning of part of titanium alloys / 2509640Invention relates to reconditioning of parts from titanium alloys by laser buildup and can be used in machine building for repair of worn-out parts. Titanium-based powder material layer 4 is applied on flaw 1 of part 2 via nozzle 3. Flow particles of said powder 5 I fed directly in zone 6 of laser beam effects 7. Protective gas 8 is used to protect against oxidation. Said powder I fed to article coaxially with laser beam 7. Material particles 5 delivered to article feature high temperature resulted from interaction with laser beam 7 to remelt article material and powder to eliminate aid flaw. Buildup is made by 4800-500 W laser beam at radiation rate of 800-100 mm/min and powder flow rate of 45-51 g/min. Under these conditions article material melting is minimum but in amount sufficient for strong adhesion between powder and article material. Structural-phase transitions occurred in buildup zone allow an optimum distribution of compression stresses in fused zone and that of thermal effects. |
 Monocrystalline welding of materials hardened in one direction / 2509639Invention relates to laser buildup of hardened weld seam on structural element substrate from refractory alloy with directed orientated of dendrites. Powder is fed and laser beam is directed on substrate surface to smelt fed powder and substrate surface layer to obtain dendrites 31 in surface layer oriented in direction of substrate dendrites 32. Parameters of laser buildup are as follows: beam scanning rate, laser power, beam diameter, powder stream focus and/or powder flow rate are set to ensure local orientation of temperature gradient 28 at crystallisation front 19 smaller than 45° towards substrate dendrite direction 32 for dendrite 31 in substrate 4. Beam scanning rate is set equal to 30-100 mm/min, preferably 50 mm/min and/or laser power is set equal to 200-500 W, preferably 300 W, and/or beam diameter at substrate surface is set equal to 3-6 mm, and/or powder flow rate is set to 300 mg/min to 600 mg/min, preferably 400 mg/min. |
| Method of making composite coatings by coaxial laser surfacing / 2503740 Part surface to be built up is cleaned, flushed and jet blast to roughness to ensure required coating adhesion and compressed air blowing. Part surface adjoining buildup area are additionally cleaned and flushed. Powder material is prepared and fed by two proportioners to part surface buildup area by argon flow for surfacing by pulse laser beam in argon medium. One proportioner feeds reinforcing nonmetallic dispersed powder of sintered tungsten carbide in 80.0-150.0 mcm-fraction while another one feeds metallic powder of cobalt alloy B3K in 53-106 mcm-fraction. Surfacing is performed in at least two layers by 2 kW laser beam at its displacement at 2 m/min. In first layer buildup, tungsten carbide powder and cobalt alloy powder are fed at 1:4 ratio while in second layer buildup said ratio makes 1:5. |
 Method of pulse laser building up of metals / 2502588Proposed method of pulse laser deposition on 3D surfaces of metals can be used in machine building for reconditioning of machines and mechanisms and tools. Filler is fed and subjected to pulse laser radiation along with deposition zone. Every pulse of laser radiation is amplitude modulated. Deposition of metal is effected in protective medium of inert gas, for example, argon and helium. |
 Method of producing heat-resistant coating / 2492980Invention relates to metallurgy and machine building and may be used for surface hardening and reconditioning of machine assembly units and parts. Self-fluxing NiCrBSi-system powders are applied on substrate by gas-powder laser deposition to perform annealing at 1000-1075°C for 1-4 hours. |
 Method of depositing filler corrosion-erosion powder on part steel surface / 2478028Invention relates to protection of steel surfaces against erosion including that caused by cavitation, by building up corrosion-erosion-resistant powder. First, corrosion-erosion-resistant self-fluxing filler powder material and sieved and calcined. Heating zone is created at part surface by continuous laser beam to feed filler material thereto, to fuse it and mix with fused mother material. Building-up is carried out on shifting laser beam at constant rate and invariable lens focus position relative to processed surface at radiation density q varied in the range of 5×108 ≥ q ≥ 3×108 W/cm2, and at mother metal-to-built-up metal ratio of γ = 5-15%. |
 Method of connecting two components / 2477678Invention relates to jointing structural elements together, particularly, in aerospace engineering for butting reinforcing strap, floating support of rib or stringer with panel, for example, wing or fuselage panel. Alternatively, said joint may be used for connecting adjacent layers of laminar structure. Structure first component 55 is prepared by building up ordered set of ledges 56, 57 on its side in the area of joint with another component. Every said ledge is built up as sequence of layers using additive process. Building up of every layer is performed at selected areas of component joint by directing laser beam fro laser head to applied layer of material or by feeding powder material to be fixed thereon thermally by laser beam, or by feeding hot material via nozzle. Components are jointed together by embedding ordered set of ledges of the first component into second one. |
 Method and device for surface marking by controlled intermittent nanostructures / 2494035Invention can be used for object or article marking for its identification, tracking and authentication. First step 500 of data encoding to the image including the magnitudes representing encoded data is performed. Second step 506-514 of point marking of a section of said surface is performed using polarised laser beam to form oriented nanostructures on said surface or therein. Polarisation of laser beam at every point of marking is modulated proceeding from the value of said image point. In compliance with some versions, marking step comprises using the pulse laser with pulse length smaller than 10×10-12 seconds and the means for polarisation of light emitted by said laser source to reach aforesaid surface along polarisation axis that can vary subject to signal received thereby. |
FIELD: physics, optics.
SUBSTANCE: invention relates to laser material processing, particularly a method for laser fusion using an ablation coating. The method involves determining the surface region of a fusible substance where fusion is to be carried out and depositing a layer of ablation material thereon; laser irradiation of said ablation layer until fusion of the substance and complete removal of said ablation layer; the laser radiation power, irradiation mode and thickness of the ablation layer are selected depending on the radiation absorption coefficient of the fusible substance during transition thereof to a liquid phase; further depositing new portions of ablation material on the irradiated area during irradiation with removal of the irradiated ablation material until the onset of fusion of said substance.
EFFECT: fusing a material with laser radiation with an arbitrary wavelength independent of whether said wavelength belongs to the absorption region of the fused material.
3 cl, 3 dwg, 1 ex
The invention relates to the field of laser treatment of materials, in particular to laser fusion.
For the implementation of laser melting traditional way beam laser focus (good quality beam focusing can be optional) on-site surface portion of molten substances (see Figure 1). The radiation is delivered to or by a series of successive pulses, or continuously, until it reaches the melting of substances. If you want to melt layer of matter, the size of the surface of which by far exceed the focal spot diameter of the laser beam, is scanning the irradiation of the surface of matter. Figure 1 shows the traditional scheme of laser melting, where 1 - beam laser radiation, 2 - focusing system (depending on the quality of the beam can be optional), 3 - layer of molten substances, 4 - area of intense heat.
Laser melting on the above traditional method is only feasible if the wavelength of the laser radiation belongs to the field of absorption of electromagnetic radiation spectrum of molten substances. Only when this condition occurs the absorption of laser radiation in a layer of a substance and its heating. Accordingly, for melting different substances require different lasers with a suitable wavelength. For many substances such lasers can not exist. In addition, the use of some types of lasers, such as gas, can be-low-tech as a result of their large size and complexity of operation.
The aim of the present invention is to provide an opportunity laser melting arbitrary substances irrespective of ownership of the laser wavelength to the field of absorption of molten substances, i.e. laser radiation with arbitrary wavelengths.
The technical result of the present invention method is achieved by laser melting is carried out using ablative (receding under irradiation) coating material which is absorbing for the wavelength of the laser radiation. The method contains the following consecutive steps (activities): first determine the surface area of molten substances, which must be melting; then referred to a specific surface area put a layer of ablative material; then perform exposure to a laser beam mentioned layer ablative coating to melting substances and complete removal of ablative material. The intensity of the laser radiation, radiation treatment and thickness ablative layer is selected depending on the values of the coefficient of absorption of radiation of molten substances at its transition in liquid phase.
In particular, applying a layer of ablative material may be exercised only part of these surface area of substance, but its characteristic size should be not less than the diameter of the laser beam.
In particular, in the process of irradiation by removal of the ablative layer on the irradiated area can additionally be applied more portions ablative material, before the onset of melting mentioned layer of molten substances.
In particular, the laser beam irradiation of molten substances may further focus on plot with ablative coating.
The essence of the proposed method consists in the following.
Figure 2 shows a diagram of the laser melting according to the present invention, where 1 - beam laser radiation, 2 - focusing system, 3 - layer of molten substances, 4 - area of intense heat, 5 - site ablative coating.
Before laser irradiation on the surface area of the portion (layer) of the substance (3), which should melt, put a layer of ablative, i.e. disappearing under irradiation (1), material (5). Ablative material (5) shall meet the following minimal requirements:
- must have good absorption coefficient for the used wavelength laser radiation (1)to effectively transform the energy of absorbed radiation into heat;
- must not react with the molten matter (3) neither when applied on the surface of molten substances (3)nor during irradiation, so as not to disrupt the chemical composition of molten substances (3);
- should have a low thermal resistance to heat quickly passed into molten substance (3);
- must be removed from the surface of molten substances under the influence of laser radiation (evaporate or burn), forming products of combustion in gaseous phase, which do not enter into chemical reactions with molten substance (3)that on the surface of molten substances (3) not formed layer consisting of the remnants ablative material and products of its combustion.
The characteristic size of the plot with ablative coating (5) depending on size of the surface layer of molten substances and should not be less than the diameter of the laser beam.
To make a melting substances, beam (1) laser guide (focus) on the surface of a substance with ablative coating (5). The radiation energy is absorbed in the ablative layer (5) and heats it. Thus ablative layer (5) converts the energy of radiation into heat and serves as the surface of a source of heat, the heat from which heat is distributed in the surface layer (4) of molten substances (3) and heats it up to the melting temperature.
In the General case, the power of radiation, exposure mode and thickness ablative layer (5) are selected depending on the coefficient of absorption of radiation of molten substances (3) during transition it into a liquid phase. However, there are two cases:
1) If in the molten state of matter (3) becomes absorbing, it is sufficient that at the time of the melting ablative coating (5) on its surface is completely withdrew within spots incident radiation (evaporated or burned)by opening the surface of molten substances (3). Formed in this place a drop of melt already will absorb radiation and then will start working the traditional mechanism of this process is due to the absorption of radiation in matter itself. The primary drop melt acts as the seed for the development of the process of melting by volume substances (3). In this case, enough drawing ablative coating (5) only a part of the surface layer of molten substances.
2) If, in the molten state of matter (3) remains that weakly absorb or transparent to laser radiation, the ablative coating(5) within spots incident radiation (1) should be removed only after the onset of melting substances (3). In this case ablative coating (5) applied on the entire surface layer of molten substances (3). In addition, if the removal of irradiated ablative plot takes place before the onset of melting, you can add the new batch of ablative material (5) of the irradiated area in the process of irradiation.
In both these cases the surface scan laser beam continues until you have completed the melting of the entire layer of the substance and the complete removal of ablative coating.
If the laser melting is carried out in air or in a different atmosphere, in which there is a burn-ablative layer or its vapours, the funds allocated by the combustion heat is additional heating of the surface layer of the substance, which facilitates and accelerates its melting.
Thus, in contrast to traditional technologies of laser melting the proposed method allows to use the same laser melting of various substances regardless of the values of the wavelength of the radiation spectrum of absorption of molten substances.
The example of realization of this method
Performance and high efficiency of the proposed method of laser melting were we experimentally proven by the example of such a refractory material, such as aluminium oxide Al 2 O 3 (sapphire), which has a melting point 2046,5 C With normal pressure. This material is widely used for manufacturing of abrasive materials and tools, micropositos and elements of precision mechanics, substrates chips and vacuum-tight metal-ceramic units, medical instruments.
In the case of refractory materials (with a melting point of about 2,000 C and higher) for ablative coating (5), as we have established, ideal graphite. Its physical properties best satisfy all of the above mentioned requirements to the properties ablative material:
- it is chemically inert, even at higher temperatures (with some exceptions);
- has a very high absorption of electromagnetic radiation in wide range: 0,93-0.75 for wavelength 0.4 to 4 mm at a temperature of 20 C depending on varieties of graphite and extent the roughness of its surface;
- has high conductivity: 20-5,3 W/cm·at temperatures 300-1000 To depending on varieties of graphite;
- at a temperature of about 2000 degrees C at normal pressure graphite sublimates, that is transformed into the gas phase, bypassing liquid;
- in the air (oxygen) pairs of graphite burn at temperatures above 400 to 600 degrees Celsius in depending on the species of graphite, producing carbon dioxide.
In our experiments melting sapphire using ablative coating of graphite were made continuous focus (using the system 2 of figure 2) radiation powerful diode laser with a wavelength of 980 nm. As can be seen from figure 3 presents the dependence of the coefficient of transparency sapphire on the wavelength of the incident radiation, it is adjudged to be in an area of high transparency of sapphire. I.e. diode lasers, the characteristic wavelengths of radiation which mostly belong to the interval λ=808-980 nm, may not be used for the laser melting of sapphire in the traditional way.
1. The method of laser melting using ablative coatings, including the following sequential operations in which: - determine the surface area of molten substances, which must be melting; - applied on the mentioned specific surface area layer ablative material; - carry out laser irradiation mentioned ablative material before full removal mentioned ablative layer, and the power of laser radiation, radiation treatment and layer thickness ablative material is chosen depending on the ratio uptake of molten substances at its transition in liquid phase; - in addition put the new batch of ablative material on the irradiated area during irradiation at removal of irradiated ablative section before the onset of melting the substances.
2. The method according to claim 1, characterized in that in the exercise of drawing a layer ablative material on the surface area of molten substances characteristic size of the plot with ablative coating choose not less than the diameter of the laser beam.
3. The method according to claim 1 distinguished by that the laser radiation by irradiation focus on the plot with ablative coating.