Amorphous foil in-line mechanical scribe method for aligning magnetic domains and reducing core loss

Abstract

This invention relates to reducing core losses in soft magnetic applications using amorphous foil as the core material. It is well known that amorphous foil exhibits lower losses compared to crystalline silicon steel laminations. Compared to prior art amorphous materials, it has been found that mechanical scribing on the surface of soft magnetic laminations (including wound cores in power regulation devices such as transformers) can reduce losses by 10-40%. The scribing process introduces control over magnetic domains, thereby mitigating flux reversal.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application No. 17 / 033,301, filed September 25, 2020, which is expressly incorporated herein by reference in its entirety. Technical Field

[0003] The purpose of this invention is to reduce core losses in soft magnetic amorphous materials by applying in-line mechanical scribing during the processing of amorphous laminates. Amorphous laminates can be fabricated into wound core shapes for use in many power conditioning devices, primarily for reducing losses in high-efficiency distribution transformers. Background Technology

[0004] Domain refinement is a common technique for reducing losses in conventional silicon steel laminated cores, and its mechanism is well documented. The pinning positions of the domains mitigate inversion and are applied to the laminate in a direction perpendicular to the casting direction. This can be accomplished through numerous processes in conventional silicon steel laminates.

[0005] For example, U.S. Patent No. 4,685,980 (the contents of which are incorporated herein by reference in their entirety) teaches a method for applying pinning positions to silicon steel laminations by laser processing of the strip surface. Laser scribing is a common method for reducing core losses, and several patents teach this method. This typically involves using laser heating to locally recrystallize the silicon steel lamination. U.S. Patent Publication No. 2003 / 0121566 (the contents of which are incorporated herein by reference in their entirety) uses a mechanical contact method that includes introducing strain into the strip by applying transverse grooves to the lamination during the rolling stage of production or in a separate processing step thereafter. These grooves then help orient magnetic domains during crystal growth after a heat treatment stage. U.S. Patent No. 5,013,373 (the contents of which are incorporated herein by reference in their entirety) uses a chemical etching process to introduce mechanical grooves into silicon steel laminations.

[0006] The production of amorphous foils differs from that of silicon steel because amorphous foils require relatively high cooling rates to suppress crystallization. These high cooling rates limit the thickness of the foils to less than 100 micrometers, with 15 to 30 micrometers being more common. U.S. Patent No. 4,331,739 (the contents of which are incorporated herein by reference in their entirety) teaches the planar flow melt spinning (PFMS) process, which is currently the preferred method for producing amorphous foils. PFMS is typically carried out at casting speeds of 15 to 45 m / s, in which the foil is cast and wound synchronously, making it difficult to achieve any type of in-line scribing during the production process.

[0007] Laser scribing of amorphous laminates has been described in U.S. Patents 4,915,750, 4,724,015, and 9,290,831 (the contents of each of which are incorporated herein by reference in their entirety), where laser patterning is applied after the initial production steps. Laser scribing requires individual processing of the laminates, and the yield of amorphous laminates with a nominal thickness of 25 micrometers is lower than that of silicon steel laminates, which can be 10 to 50 times thicker than amorphous foil. The additional costs associated with processing thin laminates are one of the main reasons why laser scribing has not been widely used for amorphous materials. Due to the high cost of the materials resulting from the additional processing, mechanical scribing of amorphous laminates has not yet been widely commercialized.

[0008] Since processing speeds are typically in the range of 20 to 30 m / s, online methods for scribing amorphous laminates are challenging. U.S. Patent No. 10,468,182 (the contents of which are incorporated herein by reference in their entirety) discusses methods for introducing mechanical scribing during processing, which involves forming a template pattern on the surface of a cast substrate by scraping the substrate with a wire brush during processing, or introducing undulations on the strip surface by controlling the temperature distribution in a melt nozzle. Summary of the Invention

[0009] The scribing of this invention can be achieved online in amorphous materials during foil production by feeding material onto a quenched substrate through controlled capillary vibration of a molten metal pool (puddle), resulting in the casting of mechanical patterns into the amorphous stack. This patterning refines magnetic domains and reduces core losses. The pattern in the foil is a reduction in local thickness captured during capillary vibration. Under controlled conditions, the pattern completely covers the width direction of the foil and has uniform spacing.

[0010] The casting conditions for producing amorphous foils have fundamental stability limitations. The PFMS process is based on the requirement that molten metal must flow onto a rotating cooling wheel substrate for rapid quenching into a continuous foil. The wheel's linear velocity, the applied pressure to the molten metal, the hydrostatic pressure of the metal, and the gap between the nozzle and the wheel are the main control parameters of the PFMS process. Too slow a wheel speed results in excessively thick strips that cannot form amorphous strips, while too high a speed hinders solidification and prevents the formation of a fully quenched foil. Too high an applied pressure to the molten metal flow causes process overflow, preventing strip formation. Similarly, too low an applied pressure will not supply enough molten metal to form a complete strip. The gap between the nozzle supplying the molten metal and the cooling wheel is also an important control parameter, as this gap provides hydrodynamic resistance to the molten metal flow and allows the flow to form a stable sheet in the width direction. A gap that is too large does not effectively restrict the flow, while a gap that is too small restricts the flow to the point where the metal freezes in the nozzle slot instead of flowing onto the casting wheel. The process can operate within these fundamental stability limitations. However, it has been determined that under selected process conditions, capillary vibrations in molten metal can be induced and controlled at a specific frequency to form uniform scribing patterns in amorphous stacks. Attached Figure Description

[0011] The invention will be more fully understood and its advantages will become apparent when the following figures and detailed description of the embodiments are taken into account, in which:

[0012] Figure 1 A schematic diagram of the PFMS process is shown.

[0013] Figure 2 The contact area where a pool of molten metal is formed between the quenched substrate and the nozzle is shown.

[0014] Figure 3 An optical image of an amorphous stripe with a mechanically scribed pattern is shown.

[0015] Figure 4A The visual pattern observed in the mechanically scribing strip is shown; Figure 4B A cross-sectional view of the strip is shown, which reveals localized thickness reduction at the scribbled location; Figure 4C The results of the surface photometer measurements on the scribed foil surface are shown.

[0016] Figure 5 This is a schematic diagram of magnetic domains in a strip and how adding lines reduces the width of the magnetic domains.

[0017] Figure 6 is a schematic diagram of a contoured nozzle that matches the thermal deformation of the casting wheel to maintain a uniform gap height spacing.

[0018] Figure 7AThe function relationship between the scribe line wavelength and the gap height is shown; Figure 7B The relationship between core loss and gap height is shown; Figure 7C The relationship between core loss and the scribed wavelength is shown.

[0019] Figure 8 This diagram shows a typical laced distribution transformer core for amorphous transformers.

[0020] Figure 9 The Fe alloy used for laminated materials is shown. 81 B 14.7 Si4C 0.3 The core loss in an amorphous magnetic core is a function of the induction level, and the laminated material is made of typical amorphous foil, optimal scribing foil, and minimum scribing foil.

[0021] Figure 10A A schematic diagram showing a scribing pattern covering 75-100% of the foil surface from edge to edge; Figure 10B The foil surface is shown with a coverage of 25-50% from edge to edge.

[0022] Figure 11 The Fe alloy used for laminated materials is shown. 79 B 11.6 Si 9.3 C 0.1 The core loss in an amorphous magnetic core is a function of the induction level, and the laminated material is made of typical amorphous foil, optimal scribing foil, and minimum scribing foil. Detailed Implementation

[0023] As defined herein, a “magnetic domain” is a region in which the magnetic fields of atoms are grouped together and aligned. “Domain refinement” refers to techniques for reducing core losses in laminated materials. The term “applied pressure” as used herein refers to the combination of a metal hydrostatic head and any additional gas pressure applied to the crucible. The “free face” of the foil refers to the side that does not contact the cooling wheel substrate during processing. Unless otherwise stated, descriptions of the characteristics of the scribing pattern on the foil (including wavelength, depth, width, etc.) herein refer to characteristics observed on the free face of the foil. “Frequency scaling” as used herein refers to the resonant frequency at which the molten metal pool is most susceptible to vibration. “Scribble” includes techniques used to create small deformations on the surface of the laminated material, resulting in domain refinement. As mentioned above, PFMS is a rapid solidification process for manufacturing thin metal strips and foils. “Gap height” refers to the distance between the nozzle and the surface of the cooling wheel, where a molten metal pool is formed during processing. As used herein, “capillary vibration” refers to the vibration of the molten metal pool caused by capillary forces during PFMS.

[0024] In a preferred embodiment, controlled capillary vibration of the molten metal pool during the PFMS process is disclosed. Figure 1 This demonstrates the characteristics of feeding molten metal from a crucible to a rotating quenching wheel via nozzles, which produces continuous amorphous foil or rapidly solidified foil. Important control parameters are the applied pressure in the crucible, the nozzle gap spacing, the nozzle internal geometry, and the wheel's linear velocity. The process can be operated in batch mode: by applying inert gas pressure to the crucible during casting to address the reduction in metal hydrostatic pressure; or in continuous mode: by maintaining the molten metal level in the crucible through an additional supply method. The applied pressure is a combination of the metal hydrostatic head and any additional gas pressure applied to the crucible.

[0025] Figure 2 The diagram shows a close-up schematic of the contact area between the nozzle and the wheel. The gap or height between the nozzle and the quenching wheel is small enough to limit the flow rate of the molten metal. The flow of the molten metal depends on the applied pressure and the gap height. The combination of gap height, applied pressure, and wheel speed is important for process stability. A wide range of process conditions can produce amorphous foils. However, among these broad conditions defining process stability limits, a set of operating parameters has been identified that allows the molten metal pool to vibrate freely at its natural resonant frequency. This vibration frequency is expressed as:

[0026] f~(σ / ρ*G 3 ) 1 / 2 ,

[0027] In the formula, ρ is the density of the molten metal, G is the gap height, and σ is the surface tension of the molten metal. Physically, this is the ratio of inertial force to capillary force within the molten pool. The viscous force in the molten metal is usually low, therefore there is almost no vibration damping, and vibration can resonate freely.

[0028] The frequency scaling of this vibration is characterized by a non-linear gap height, meaning that controlling the gap height is crucial. Under optimal process conditions, the molten pool vibration oscillates freely, capturing a mechanical pattern for each vibration cycle in the amorphous foil during processing. Figure 3 The image shows an amorphous foil free surface that captures the vibration of the molten pool. Figure 4A A schematic diagram of an amorphous foil with physical scribings on its surface is shown, with each scribing separated by a wavelength distance λ. Figure 4B The cross-section of the foil is shown, in which the scribe lines have a localized decrease in thickness of depth δ and width ω, and relatively flat portions exist between the lines. Figure 4CThe results of a series of surface photometric measurements on the free surface of the entire amorphous strip are shown. Any scribing pattern of suitable depth and width can be used with the methods described herein. In a preferred embodiment of the invention, the depth of the scribing pattern is typically 1 to 15 micrometers, and the width is typically 50 to 800 micrometers. Preferably, the depth of the scribing pattern is 1 to 5 micrometers, or more preferably, 1.5 to 3 micrometers. Preferably, the width of the scribing pattern is 100 to 500 micrometers, or more preferably, 200 to 400 micrometers. The depth of the scribing pattern can reach 95% of the thickness of the cast foil. Preferably, the scribing depth is less than 50% of the foil thickness, or more preferably, the scribing depth is 10-20% of the foil thickness. The scribing area of ​​the scribing pattern has a local reduction in thickness, and the surfaces between the scribings are relatively uniform. The spacing between the lines can be characterized by the wavelength λ. Any scribing pattern of suitable wavelength can be used with the methods described herein. In one embodiment, the wavelength is about 0.5 to 10 mm. In a preferred embodiment, the wavelength is about 1 to 5 mm, or more preferably, about 2 to 4 mm. The spacing can be defined in various ways, including: i) the length between each line, ii) the number of lines per unit length, or iii) the length spanning a specified number of lines, or iv) the total length spanning a specified number of lines divided by that number to represent the average wavelength. The wavelength data reported herein is the length spanning ten lines divided by ten. These are equivalent methods for reporting the wavelength between mechanical scribings in the foil. This wavelength can be converted to a frequency, f ~ λ / U, by dividing by the linear velocity of the quenching wheel, where U is the linear velocity of the wheel. By equalizing the vibration frequency with the frequency of the foil line spacing, a predictive relationship for controlling the pattern wavelength in the foil is determined as follows:

[0029] λ=C*U*(ρ*G 3 / σ) 1 / 2 .

[0030] In one implementation, under the experimental conditions described herein, C is a geometric constant associated with the resonance mode, experimentally found to be ~0.5. The method described herein can be applied to PFMS machining operations using any suitable alloy and any suitable casting temperature.

[0031] Due to the high heat flow rate during the PFMS process, thermal expansion of the quenching wheel may occur during casting. Variables such as quenching wheel thickness, internal cooling design of the quenching wheel, thermal conductivity of the quenching wheel, and casting line speed may affect the amount of thermal expansion. As shown in Figure 6, it was determined that the expansion of the casting wheel is generally symmetrical across the entire width of the foil, with most of the expansion occurring at the center of the edge. The thermal expansion of the wheel causes a spatial variation in the gap height along the width direction of the foil, which in turn causes the resonant vibration frequency of the molten pool to vary in the same manner. Therefore, the proportion of the scribing wavelength λ also varies in the width direction. Within a short timescale where the thermal expansion effect is negligible, the transition period of the PFMS process (from start to steady state) can produce some foils with uniform and complete scribing coverage. Thermal expansion is known to occur during PFMS processing, but the variation of the cooling wheel in the width direction and its effect on the gap height and capillary vibration have not been previously reported. It was determined that in continuous production mode or intermittent production mode after reaching steady state, it is impossible to maintain a consistent scribing pattern covering the entire width of the foil without compensating for the gap variation in the width direction. In one embodiment, capillary vibration is controlled such that the scribe lines cover more than 50% of the amorphous foil surface (from edge to edge of the strip). Preferably, they cover more than 75% of the amorphous foil surface, or more preferably, they cover more than 90% of the amorphous foil surface, or even more preferably, they cover 100% of the amorphous foil surface. In other embodiments, the coverage is at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%. Preferably, the coverage of the scribe lines on the strip is consistent throughout the casting process. That is, the scribe lines preferably cover more than 50% of the amorphous foil surface from edge to edge of the strip and from beginning to end of the roll.

[0032] As shown in Figure 6, one solution to thermal expansion is to modify the nozzle gap height in the width direction of the foil. A contour can be applied to the width direction of the ceramic nozzle to accommodate wheel expansion. Any suitable contour can be applied to the ceramic nozzle to adapt to and match wheel expansion. In one embodiment, wheel expansion is closely matched by machining an arc segment, specifically a shallow circular arc with a height of 10 to 500 micrometers and a length equal to or slightly less than the length of the nozzle groove. The arc machined into the nozzle then increases the gap spacing across the nozzle width. In a preferred embodiment, the height of the arc segment is 30 to 100 micrometers. The radius of the arc is 5 to 1000 meters. In a preferred embodiment, the radius of the arc is 50 to 100 meters. The radius of the arc depends on the total width of the nozzle, where a 100 mm nozzle groove width requires a preferably 10-meter arc, while a 250 mm nozzle groove width requires an 800-meter arc. The choice of nozzle width depends on the width of the cast strip, and therefore, the radius of the arc will also depend on the width of the cast strip. In most cases, the radius can be accurately simulated by programming a small number of linear movements of the start and end points on or near the arc. For example, the radius can be accurately simulated by programming 10 linear movements. A surface grinder with electronic axis positioning is used to apply the curve. In a preferred embodiment, the machining tolerance of the nozzle with the curve is within 50 micrometers of the desired pattern. In a more preferred embodiment, the machining tolerance of the nozzle with the curve is within 25 micrometers of the desired pattern, or more preferably, they are within 10 micrometers of the desired pattern. Figure 6C As shown, once the nozzle and wheel reach a stable operating temperature, the arc along the nozzle width allows the gap spacing to remain within 25 micrometers over the entire length of the groove. In a preferred embodiment, the gap spacing is maintained within 50 micrometers over the entire length of the groove, or more preferably, within 25 micrometers. This allows the molten metal pool to vibrate more uniformly across the entire width of the strip. However, the exact form of this thermal expansion may not be the norm, and an iterative procedure can be used to estimate the wheel expansion shape, then the curve is applied to the nozzle, tested in the PFMS process, and the shape of the curve modified based on the appearance of the strip scribing pattern. While different PFMS machines may exhibit different thermal expansion based on internal cooling methods, wheel materials, casting speeds, and other factors, the methods described herein are applicable to any PFMS equipment. For example, the process may include modifying the nozzle shape to shapes other than an arc, such as a flattened arc, a serrated step variation in the pattern, or other shapes that mirror the wheel expansion shape. In one embodiment, corresponding to a capillary vibration frequency of 2.5 to 30 kHz, the wavelength of the scribe pattern on the amorphous foil is 0.5 to 10 mm, and the casting speed is 5 to 50 m / s.

[0033] Maintaining a uniform gap height across the entire width of the strip allows for control of capillary vibrations to draw a uniform wavelength across the entire strip. Figure 7A The diagram shows how the scribing wavelength changes with the gap height. The data shown in Figure 7 corresponds to a wheel speed of 18 m / s and a nominal applied pressure of 10 kPa. The method described herein can generally use any suitable wheel speed. In one embodiment, the method can use a wheel speed of 5 to 50 m / s. Preferably, the method can use a wheel speed of 15 to 25 m / s, or more preferably, 18 to 23 m / s. The applied pressure is adjusted as the gap height changes to maintain a constant strip thickness of 25 micrometers. The method described herein can use any suitable applied pressure. In one embodiment, the method can use an applied pressure of 2 to 20 kPa. In a preferred embodiment, the applied pressure is 4 to 14 kPa, more preferably, 5 to 10 kPa. Based on the method used to obtain... Figure 7A The measurement results (in one embodiment of the invention) under the conditions where the gap height is low (typically less than 150 micrometers) generally do not exhibit a scribing pattern. Under these low gap conditions, amorphous stripes tend to have a very smooth, mirror-like surface finish. Figure 7A In the illustrated embodiment, a gap height of 200 to 400 micrometers indicates Figure 7A The measured values ​​of the scribed pattern. Similarly, in Figure 7A In the illustrated embodiment, a gap height greater than 350 micrometers results in a scribing pattern with more irregular wavelengths, less defined boundaries, and greater difficulty in measurement. In one embodiment, core losses begin to increase with further increases in gap height, and the scribing wavelengths become longer and more inconsistent in appearance. The ideal gap height for applying the scribing pattern can be determined by modifying process conditions (e.g., applied pressure, wheel speed, alloy formulation). Depending on the casting process conditions used, the ideal gap height for applying the scribing pattern to the strip can be from 75 micrometers to 1 millimeter, preferably from 75 to 400 micrometers, more preferably from 150 to 300 micrometers, and even more preferably from 200 to 230 micrometers.

[0034] A wide range of soft magnetic compositions can be used with this scribing method. The alloys generally follow the following formula in atomic percentage: Fe 100-v-w-x-y-z Si v B w P x C y M z, wherein, in addition to inevitable impurities, Si, B, P, and C are non-metals contained in the alloy that contribute to the formation of an amorphous structure, and M preferably can be certain combinations of Co, Nb, Cu, Mo, Cr, Ni, or any transition metal belonging to Groups IV to XI. One embodiment includes an alloy, wherein v = 0 to 15.2 atomic percent, w = 0 to 20.3 atomic percent, x = 0 to 15.9 atomic percent, y = 0 to 2 atomic percent, z = 0 to 66.8 atomic percent, and 15 < v + w + x + y < 30. In other embodiments, the alloy for producing the foil consists essentially of Fe 100-v-w-x-y-z Si v B w P x C y M z by atomic percent, where Fe is 78 to 84, Si is 0 to 1, B is 11 to 18, and C is 0 to 0.5. Table 1 lists examples of representative chemical elements that show a scribed pattern with wavelength λ and associated magnetic induction level B in an amorphous foil when driven in an applied field of 800 A / m.

[0035] Table 1: Soft Magnetic Amorphous Alloy Compositions Showing a Mechanical Scribed Pattern and Their B 800 values and scribed wavelengths.

[0036]

[0037] Note: There seems to be a typo in the original text where "Si is 0 to " should probably be "Si is 0 to 10" as per the context and corrected in the translation.For example, the scribing pattern can be applied to foil with a width of 10 mm to 1 meter. The width of the foil may be limited by the nozzle and casting wheel size, as well as the ability to apply the curve to the nozzle, wherein applying the curve to the nozzle keeps the gap height constant at the location where the scribing pattern is uniformly applied. In one embodiment, the method described herein can be used to scribing strips with a width of 10 mm to 260 mm, for example, the strips can be 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, 200 mm, 210 mm, 220 mm, 230 mm, 240 mm, 250 mm, and 260 mm, and any variation within these widths. The ability to cast strips with scribe patterns at these widths depends on the size of the nozzle and casting wheel, as well as the curve applied to the nozzle such that the gap height remains constant and the scribe pattern is applied uniformly. This scribe pattern can be applied to foils with a thickness of 13 to 75 micrometers. In one embodiment, the strip thickness is about 13-40 micrometers, more preferably about 13-30 micrometers. In one embodiment, λ is observed to vary between 1 and 5 mm, depending on the alloy and processing conditions. The scribe pattern can be seen covering 10% to 100% of any part of the foil surface. In one embodiment, the scribe pattern covers 10% to 100% of the strip, including edge-to-edge and head-to-tail sections on the strip reel. Depending on the chemical composition of the alloy, the magnetic induction level of the foil can vary between 0.6 and 1.8 T.

[0038] In most cases, such scribe lines in foil are not a desired feature, and existing methods attempt to avoid casting alloys with any patterns. However, it is determined that such patterns have unexpected benefits for the magnetic properties of the foil, particularly reducing losses. The capillary vibration method described herein, which applies scribe lines to the foil, allows for online application of magnetic domain control in a single step during foil production. Figure 5 A schematic diagram of the magnetic domains in the amorphous strip is shown. The mechanically scribing pattern refines the magnetic domains and reduces their width, thereby increasing the ease of flux reversal and reducing core loss.

[0039] The loss reduction found in the scribing foil is partly dependent on the end application. Typically, amorphous foil properties are reported in single-strip configurations. Each foil roll is sampled and tested in a flattened single-strip configuration according to the test methods defined in the ASTM International Standard for Amorphous Testing. This foil is primarily used in wound toroidal coil configurations or strip-shaped distribution transformer core applications, each of which has a building factor or destruction factor that introduces losses when converting from a monolithic to a core configuration. Table 2 shows embodiments of the invention, including representative sample weights and measured losses for three configurations used in Fe composition. 81 B 14.7 Si4C 0.3 The nominal foil and scribing foil. In all cases, the scribing condition results in a representative loss reduction of approximately 30%. The methods described herein can allow scribing conditions to show a loss reduction of 10% to 40%, preferably, a loss reduction of 20% to 40%. Monolithic testing can include foil samples weighing a few grams. Toroidal constructions can include a self-wound foil sheet (most commonly cylindrical) weighing from tens of grams to several kilograms. The mass of distribution transformer cores is much greater, depending on the transformer size, and can range from several kilograms to over 1000 kilograms.

[0040] Table 2: The range of core losses showing the percentage reduction in average loss for nominal amorphous foil and scribing foil tested at 1.4T magnetic induction and 60Hz frequency.

[0041]

[0042] Figure 7B The composition of one embodiment of the present invention is Fe. 81 B 14.7 Si4C 0.3 The relationship between core loss and gap height for a wound toroidal coil is shown. Here, the magnetic properties of the strip are measured by winding it into a 25 mm wide toroidal shape with an inner diameter of 40 mm, an outer diameter of 43 mm, and a core weight of 30 grams, and annealing the core with an external magnetic field. The optimal gap height for minimizing core loss is found to be between 200 and 400 micrometers. Figure 7C The core loss as a function of the scribing wavelength is shown. It can be seen that in this toroidal core construction, the optimal scribing wavelength for reducing core loss is 1.5 to 4 mm. This establishes that the gap height controls the scribing wavelength, thereby optimizing domain refinement.

[0043] Table 3 shows a list of embodiments of the present invention, including sample castings of foil using a scribing method, the foil being 213 mm wide and composed of Fe.81 B 14.7 Si4C 0.3 Core loss and excitation power measurements were performed at 1.4T and 60Hz. Here, monolithic test results are reported under optimal process conditions, with scribing used... Figure 4B λ, δ, and ω, as defined in [reference needed], are further characterized. These surface photometric measurements were performed on the free surface of the foil using a Mitutoyo surface roughness tester (model SJ-410). Here, the B80 measurement results are for the magnetometry under an applied field of 80 A / m, and the stacking factor is a measure of the stacking density, ranging between 0.875 and 0.914. The reported scribing dimensions of λ = 2 mm, δ = 3 μm, and ω = 300 μm demonstrate optimal loss reduction in the monolithic construction.

[0044] Table 3: The single strip test results show the physical and magnetic properties of the best scribing foil on the production machine.

[0045]

[0046] In the embodiments shown in Table 3, since the single-piece loss has been reduced from a typical value of 0.125 W / kg to 0.083 W / kg, when tested at an operating induction level of 1.4 T and 60 Hz, the core loss of the amorphous foil core in these embodiments is reduced by 31% compared to amorphous foil cores operated under conventional PFMS process conditions. According to the present invention, controlling the scribing pattern can generally affect the core loss by approximately 25-40%.

[0047] Example

[0048] A)Alloy composition Fe 81 B 14.7 Si4C 0.3

[0049] Example 1 – Normal Operating Conditions

[0050] Fe in atomic percentage 81 B 14.7 Si4C 0.3 Alloys are one of the conventional chemical substances used in commercial production, and various finished cores have been formed under normal operating conditions. Table 4 lists typical process parameter ranges for important control variables in the process. Standard production nozzle conditions are flat-bottomed and non-curved, which results in the observation of scribing patterns when the process conditions are consistent with those in Example 1. However, due to the lack of a curve in the nozzle, the scribing coverage is rarely in the range of 75% to 100%, and is typically 25% to 50%. Figure 9The core loss under normal operating conditions is shown compared to the optimal scribing conditions of Example 1. The core loss of the magnetic core in Example 1 is about 25% lower than that of the typical material in Example 2. At an induction level of 1.4T, the loss of Example 1 is 0.18 W / kg, and the loss of Example 2 is 0.24 W / kg.

[0051] Example 2 – Optimal Marking Conditions

[0052] Figure 8 The geometry of distribution transformer cores, typically used for amorphous foil cores, is shown. This type of core can range from approximately 10 to 1000 kg, but is more commonly 40 to 150 kg, significantly larger than the toroidal cores shown in Table 2. The final core loss depends on the core's construction; therefore, data for small toroidal cores do not always correspond to results for large transformer cores, but the trend regarding the scribing results is the same. Fe, in atomic percentage... 81 B 14.7 Si4C 0.3 The alloy is produced using an in-line scribing method, in which the nozzle profile is matched to the wheel profile. The alloy has a saturation magnetic flux density of 1.63 T. Table 4 lists typical process parameter ranges for important control variables in the process, and also lists the ranges for producing scribing patterns in the foil. Not all combinations of process conditions listed in Table 4 will successfully produce a stable PFMS process. Typically, the capillary pressure set by the gap height must balance the applied pressure that causes the molten metal flow. Therefore, a low gap height results in a high capillary pressure, which must be balanced by a high applied pressure. As the gap height changes, the applied pressure must also change inversely.

[0053] The average wavelength of the scribbled pattern is approximately 2.2 mm, with a coverage percentage ranging from 75% to 100%. Table 5 lists the geometry, scribbled coverage, and final core loss of the distribution transformer core. Figure 9 The relationship between core loss and magnetic flux density at 60Hz is shown. The core loss at 1.4T and 60Hz is 0.18W / kg.

[0054] Table 4: Normal operating parameter range of PFMS, range of optimized online scribing patterns, and range of minimized scribing patterns in foil.

[0055]

[0056] Example 3 – No-Stroke Condition

[0057] Fe in atomic percentage 81 B 14.7 Si4C 0.3Alloys are one of the conventional chemical substances used in commercial production, and various finished cores have been formed under normal operating conditions. Table 4 lists the typical process parameter ranges for cast foil with almost no scribing. The nozzle conditions here can be flat (non-curved) or curved. The gap height is at a very low end of stable operating conditions to prevent any scribing, so at this low gap level, the effect of the curve may be minimal. This results in a strip with a near-mirror finish. The coverage of this test is 0 to 25%. Figure 9 The core loss in the un-scribbled range is shown compared to the optimal scribbling conditions of Example 1. At an induction level of 1.4T, the loss in Example 1 is 0.18 W / kg, and the loss in Example 3 is 0.27 W / kg, indicating an overall reduction of 33%.

[0058] Figure 9 The diagram shows the core loss versus magnetic flux density at 60 Hz for the in-line controlled scribing foil from Example 1, compared to the normal production material from Example 2 and the scribing-free material from Example 3. All Figure 9 The data in the middle corresponds to Figure 8 The distribution transformer core structure shown is formed, annealed, and tested under the same standard conditions. US Patent No. 4,741,096 teaches a method for forming an amorphous distribution transformer core that is widely used in industry. Typical operating induction levels for amorphous transformers of this composition are 1.35T to 1.45T. For comparison, at 1.4T, the core loss at 60Hz is 0.18 W / kg for the scribe pattern of Example 1, 0.24 W / kg for the typical production material of Example 2, and 0.27 W / kg for the unscribed material of Example 3. This indicates that controlling the scribe pattern can generally affect the core loss by approximately 25% to 35%.

[0059] Table 5: Geometric structure of the distribution transformer core constructed for magnetic testing.

[0060]

[0061] (like Figure 8 As shown, A, B, C, and D are the dimensions of the magnetic core.

[0062] B) Alloy composition Fe 79 B 11.6 Si 9.3 C 0.1

[0063] Example 4 – Normal Operating Conditions

[0064] Fe in atomic percentage 79 B 11.6 Si 9.3 C0.1 The alloy is manufactured using standard operating conditions, a flat-bottomed nozzle, and a non-curved process. Casting conditions are not limited to optimal scribing levels but are allowed to vary within operational control limits. Here, a scribing pattern exists, but the coverage percentage ranges from 25% to 50%, and the core loss measured at 1.3T and 60Hz is 0.22W / kg. Figure 10A A schematic diagram showing the surface condition of scribing foil with a coverage of 75% to 100% is displayed. Figure 10B Typical surface conditions of scribing foil with a coverage of 25% to 50% are shown.

[0065] Figure 11 The results show the relationship between core loss and magnetic induction level at 60 Hz for in-line controlled scribing foil with a coverage of 75 to 100% from Example 4, compared to the 25 to 50% scribe coverage material from Example 5. Figure 11 The data in the middle corresponds to Figure 8 The magnetic core structure shown is formed, annealed, and tested under the same standard conditions. Core loss is reduced by 28% when the scribing coverage is 75% to 100%, compared to when the coverage is only 25% to 50%.

[0066] Example 5 – Optimal Marking Conditions

[0067] Fe in atomic percentage 79 B 11.6 Si 9.3 C 0.1 The alloy was produced using an in-line scribing method, in which the nozzle curve is matched to the wheel profile. The alloy has a saturation magnetic flux density of 1.56 T. The conditions used to optimize the scribing process in Table 4 also apply here. Here, the average wavelength of the scribing pattern is approximately 2.5 mm, and the coverage percentage is 75% to 100%. Due to the low saturation magnetic flux density of the alloy, the operating magnetic flux density of the transformer using this alloy is low. Therefore, losses were evaluated at 1.3 T and 60 Hz, showing a core loss of 0.16 W / kg.

[0068] The foregoing disclosure is for illustrative purposes only and is not intended to limit the invention. Since those skilled in the art will conceive of modifications to the disclosed embodiments in accordance with the spirit and essence of the invention, the invention should be interpreted as encompassing all contents within the appended claims and their equivalents.

Claims

1. A method of improving amorphous foil core loss performance, the amorphous foil produced by planar flow melt spinning (PFMS), the method comprising: mechanically scribing the amorphous foil having a width of 75 to 260 millimeters at intervals of a controlled wavelength, by controlling capillary oscillations in a molten metal pool formed between a crucible nozzle and a quench wheel at a controlled frequency, continuously forming a uniform scribe pattern across the width of the amorphous foil, wherein a gap height between the nozzle and the quench wheel is kept constant across the width of the foil, thereby spacing the scribe pattern on the amorphous foil at the controlled wavelength, wherein, the frequency of the capillary oscillations is represented by the equation: f = (G / ρ)1 / 2 (σ / G)1 / 2 wherein p is the density of the molten metal, G is the gap height, s is the surface tension of the molten metal, the frequency of the capillary oscillations is dependent on the gap height, ， shaping the nozzle to match the thermal distortion of the quench wheel, wherein the scribing is applied on-line while the amorphous foil is being cast. the capillary oscillations are controlled such that the scribe wavelength of the amorphous foil is 0.5 to 10 millimeters.

2. The method of claim 1, wherein, the scribe pattern formed on the amorphous foil has a depth of 1 to 15 microns.

3. The method of claim 1, wherein, the scribe pattern formed on the amorphous foil has a width of 50 to 800 microns.

4. The method of claim 1, wherein, the gap height is kept at 75 to 400 microns to control the scribe wavelength across the width of the foil.

5. The method of claim 1, wherein, the capillary oscillations are controlled such that the scribe pattern covers greater than 50% of the amorphous foil surface.

6. The method of claim 1, wherein, the capillary oscillations are controlled such that the scribe pattern covers greater than 75% of the amorphous foil surface.

7. The method of claim 1, wherein, the capillary oscillations are controlled such that the scribe pattern covers greater than 90% of the amorphous foil surface.

8. The method of claim 1, wherein, the scribe pattern is formed by capillary oscillations in a molten metal pool, the frequency of the capillary oscillations is represented by the equation: f = (G / ρ)1 / 2 (σ / G)1 / 2 wherein p is the density of the molten metal, G is the gap height, s is the surface tension of the molten metal, the frequency of the capillary oscillations is dependent on the gap height.

9. An amorphous foil having a width of 75 to 260 mm, having a scribe pattern with a wavelength of 0.5 to 10 mm, wherein, the scribe pattern covers greater than 50% of the amorphous foil surface. ， the scribe pattern covers greater than 75% of the amorphous foil surface.

10. The amorphous foil of claim 9, wherein, the scribe pattern covers greater than 90% of the amorphous foil surface.

11. The amorphous foil of claim 9, wherein, M is selected from the group consisting of Co, Nb, Cu, Mo, Cr, Ni, and combinations thereof.

12. The amorphous foil of claim 9, wherein, the scribed foil has a saturation magnetic induction of 1.6 to 1.66 T.

13. The amorphous foil of claim 9, wherein, The composition of the foil includes, in atomic percent and unavoidable impurities, where Si, B, P, and C are non-metallic elements added to help form an amorphous structure; M is selected from the group consisting of Group IV to Group XI metallic elements and combinations thereof, v = 0 to 15.2, w = 0 to 20.3, x = 0 to 15.9, y = 0 to 2, z = 0 to 66.8, and 15 < v + w + x + y < 30.

14. The amorphous foil of claim 13, wherein, the scribed foil has a saturation magnetic induction of 1.4 to 1.6 T.

15. The amorphous foil of claim 13, wherein, The composition of the foil consists essentially of, in atomic percent Fe 78 to 84, Si 0 to 10, B 11 to 18, and C 0 to 0.

5.

16. The amorphous foil of claim 13, wherein, the foil has a thickness of 13 to 75 microns.

17. The amorphous foil of claim 13, wherein, the amorphous foil having a scribe pattern with a wavelength of 1 to 5 millimeters, the amorphous foil tested in a monolithic configuration, the amorphous foil having reduced core loss, the core loss less than 0.08 W / kg when tested at 1.4 T, 60 Hz, the core loss less than 0.06 W / kg when tested at 1.3 T, 60 Hz.

18. The amorphous foil of claim 9, wherein, the foil has a lamination factor of 0.87 to 0.

92.

19. The amorphous foil of claim 9, wherein, the scribe pattern is formed by capillary oscillations in a molten metal pool, the frequency of the capillary oscillations is represented by the equation: f = (G / ρ)1 / 2 (σ / G)1 / 2 wherein p is the density of the molten metal, G is the gap height, s is the surface tension of the molten metal, the frequency of the capillary oscillations is dependent on the gap height; 20. The amorphous foil of claim 9, wherein, The foil has a saturation magnetic induction of 1.63 T, and the composition of the foil consists essentially of Fe 80.0 wt% Si 20.0 wt% 21. The amorphous foil of claim 9, wherein, The foil has a saturation magnetic induction of 1.56 T, and the composition of the foil consists essentially of Fe 80.0 wt% Si 20.0 wt% 22. The amorphous foil of claim 9, wherein, ​ 23. An amorphous magnetic core comprising an amorphous foil having a width of 75 to 260 millimeters, having a scribe pattern having a wavelength of 1 to 5 millimeters, wherein, ​ ， ​ The amorphous foil is wound into a ring-shaped magnetic core or a strip-shaped power distribution transformer magnetic core, and the amorphous magnetic core has reduced core loss, the core loss being less than 0.2 W / kg when tested at 1.4 T, 60 Hz, and the core loss being less than 0.17 W / kg when tested at 1.3 T, 60 Hz.

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