Microalloyed lead-based refrigeration alloy and microspheres thereof, and preparation method and application of microspheres

Abstract

The invention relates to a microalloyed lead-based refrigeration alloy, microspheres of the microalloyed lead-based refrigeration alloy, and a preparation method and application of the microspheres. The lead-based refrigeration alloy comprises a main element Pb, a first alloying element and a second alloying element, the first alloying element comprises Sb; the second alloying element comprises any one or a combination of at least two of Ag, Te or Cu; the lead-based refrigeration alloy is prepared from the following components in percentage by mass: 4.0 to 4.5 percent of first alloying element, 0.30 to 0.60 percent of second alloying element and the balance of Pb. Through a multi-component microalloying mode, the dosage of alloying elements is reduced, the specific heat of the material is not excessively influenced while grains are refined, the plasticity and toughness are improved and the hardness is improved, a pelletizing process of the refrigeration alloy microspheres is provided, the preparation process is simple and efficient, the particle size distribution of a finished product is narrow, and industrial production is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature refrigeration, and in particular to a microalloyed lead-based refrigeration alloy and microspheres thereof, and a preparation method and application of the microspheres. Background Art

[0002] Low temperature refrigeration technology is widely used in aerospace, biomedicine and cutting-edge scientific research, and has extremely important strategic significance. GM (Gifford-Mcmahon) refrigerators achieve refrigeration through the principle of adiabatic degassing and are currently the most widely used low temperature refrigeration method. The cold storage device is the energy storage device in the GM refrigerator, which is filled with high heat capacity cold storage filler to exchange heat with the refrigeration cycle working fluid.

[0003] Among them, the selection of cold storage materials varies according to the temperature zone. For example, using copper or stainless steel in a metal mesh as a cold storage material can reduce the temperature from room temperature to 50K; in the low temperature range below 50K, lead has a higher volume specific heat capacity than other materials and is cheap, so it is widely used as a cold storage material in 10K-class low-temperature refrigerators. However, the Vickers hardness of single element Pb is HV 0.05 The hardness is about 10.0. For the continuous operation of the refrigeration machine for 10,000 hours, such a low hardness cannot guarantee the structural stability of the filler during long-term service. The existing method usually adopts the method of adding 5.0-10.0wt.% of Sb element to the Pb matrix, which can effectively improve the hardness, but will reduce the volume specific heat capacity of the material and affect the refrigeration effect of the filler.

[0004] In addition, HoCu was prepared by atomization or centrifugation. 2 Low-temperature refrigeration microspheres have been widely used, but there has been a lack of effective spheroidization methods for low-melting-point, low-strength low-temperature refrigeration microspheres such as Pb, Bi, Zn and Sn.

[0005] Therefore, how to improve the hardness and plasticity of lead-based refrigeration materials without affecting their specific heat, and provide an industrially feasible and efficient ball-making method, is of great practical significance. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a micro-alloyed lead-based refrigeration alloy and its microspheres, a preparation method and use of the microspheres. Compared with the prior art, the present invention reduces the amount of alloying elements through multi-component micro-alloying, while refining the grains, improving plasticity and toughness and increasing hardness, without excessively affecting the specific heat of the material, and can prepare refrigeration alloy microspheres. The preparation process is simple and efficient, the finished product has a narrow particle size distribution, and is conducive to industrial production.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a microalloyed lead-based refrigeration alloy, the lead-based refrigeration alloy comprising a main element Pb, a first alloying element and a second alloying element;

[0009] The first alloying element includes Sb;

[0010] The second alloying element includes any one of Ag, Te or Cu or a combination of at least two thereof;

[0011] The lead-based refrigeration alloy comprises, by mass percentage, 4.0-4.5wt.% of a first alloying element, 0.30-0.60wt.% of a second alloying element, and the remainder is Pb.

[0012] In the present invention, in view of the problem that Pb single substance has poor mechanical strength and is difficult to withstand the test of long-term operation of low-temperature refrigerators, a first alloying element including Sb and a second alloying element Ag, Te or Cu is added to the Pb matrix, and the addition amounts of the first alloying element and the second alloying element are strictly controlled, that is, the Vickers hardness of the lead-based refrigeration alloy can be increased to HV 1000 by a microalloying method. 0.05 It is significantly improved, effectively overcoming the defects of soft and easy deformation of Pb spheres, improving the maintenance-free performance of low-temperature refrigerators, and not affecting the specific heat of the material too much, ensuring the refrigeration effect of the filler.

[0013] The mass percentage of the first alloying element is 4.0-4.5wt.%, for example, it can be 4.0wt.%, 4.1wt.%, 4.2wt.%, 4.3wt.%, 4.4wt.% or 4.5wt.%, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable; the mass percentage of the second alloying element is 0.30-0.60wt.%, for example, it can be 0.30wt.%, 0.40wt.%, 0.50wt.% or 0.60wt.%, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0014] Preferably, the Vickers hardness of the lead-based refrigeration alloy is HV 0.05 The range of the numerical value is 14.0-16.0, for example, it can be 14.0, 14.2, 14.4, 14.6, 14.8, 15.0, 15.2, 15.4, 15.6, 15.8 or 16.0, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] Preferably, the second alloying element comprises 0.10-0.30wt.% Ag by mass percentage, for example, 0.10wt.%, 0.12wt.%, 0.14wt.%, 0.16wt.%, 0.18wt.%, 0.20wt.%, 0.22wt.%, 0.24wt.%, 0.26wt.%, 0.28wt.% or 0.30wt.%, 0.06-0.20wt.% The Cu content may be, for example, 0.06wt.%, 0.08wt.%, 0.10wt.%, 0.12wt.%, 0.14wt.%, 0.16wt.%, 0.18wt.% or 0.20wt.%, and the Te content may be, for example, 0.06wt.%, 0.08wt.% or 0.10wt.%, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0016] In a second aspect, the present invention provides a lead-based refrigeration alloy microsphere, wherein the lead-based refrigeration alloy microsphere contains the microalloyed lead-based refrigeration alloy described in the first aspect of the present invention.

[0017] The lead-based refrigeration alloy microspheres provided by the present invention are suitable for commercial refrigerators, have good volume specific heat capacity and mechanical properties, can achieve good refrigeration effects while meeting the needs of continuous operation of the refrigerator, and are low in cost and economical.

[0018] Preferably, the particle size of the lead-based refrigeration alloy microspheres is 150-500μm, for example, it can be 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 220μm, 240μm, 260μm, 280μm, 300μm, 320μm, 340μm, 360μm, 380μm, 400μm, 420μm, 440μm, 460μm, 480μm or 500μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] In the present invention, under optimal conditions, the yield of the lead-based refrigeration alloy microspheres with a particle size of 150-500 μm is ≥90wt.%.

[0020] Preferably, the fluidity of the lead-based refrigeration alloy microspheres is (2.10-2.41) s / 50g, for example, it can be 2.10s / 50g, 2.20s / 50g, 2.30s / 50g or 2.41s / 50g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, the bulk density of the lead-based refrigeration alloy microspheres is 6.27-6.60 g / cm 3, for example, it can be 6.27 g / cm 3 、6.30g / cm 3 、6.32g / cm 3 、6.34g / cm 3 、6.36g / cm 3 、6.38g / cm 3 、6.40g / cm 3 、6.42g / cm 3 、6.44g / cm 3 、6.46g / cm 3 、6.48g / cm 3 、6.50g / cm 3 、6.52g / cm 3 、6.54g / cm 3 、6.56g / cm 3 、6.58g / cm 3 or 6.60g / cm 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the tap density of the lead-based refrigeration alloy microspheres is 6.85-7.20 g / cm 3 , for example, it can be 6.85g / cm 3 、6.90g / cm 3 、6.95g / cm 3 , 7.00g / cm 3 , 7.05g / cm 3 , 7.10g / cm 3 , 7.15g / cm 3 or 7.20g / cm 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0023] In a third aspect, the present invention provides a method for preparing the lead-based refrigeration alloy microspheres as described in the second aspect of the present invention, the preparation method comprising the following steps:

[0024] (1) charging corresponding metal elements into a crucible with a microporous sheet at the bottom according to the mass percentage, and then performing vacuum induction melting to obtain an alloy melt;

[0025] (2) placing a transmission device into the alloy melt obtained in step (1), disturbing the alloy melt at the microporous sheet through the transmission device, forcing the alloy melt to be squeezed out from the holes of the microporous sheet, and then solidifying to obtain lead-based refrigeration alloy microspheres.

[0026] The preparation method provided by the present invention can meet the needs of preparing low-melting-point, low-strength, low-temperature refrigeration microspheres, and the transmission device used in the present invention utilizes the piezoelectric characteristics of piezoelectric ceramics, which is a near-net-shape forming method. It only requires a simple modification of the vacuum induction furnace. By controlling the parameters such as the circular hole diameter, piezoelectric frequency and heating power of the microporous sheet, the particle size of the microspheres can be regulated. The preparation process is simple and efficient, and the technical difficulties of domestic industrial preparation of lead-based refrigeration alloy microspheres are solved. In addition, the above preparation method is not only applicable to the preparation of lead-based refrigeration alloy microspheres, but also applicable to the preparation of single substances or their alloy microspheres such as Bi, Zn, Sn or Cu.

[0027] Preferably, the preparation method further comprises step (3): screening the lead-based refrigeration alloy microspheres obtained in step (2) to obtain lead-based refrigeration alloy microspheres of target particle size.

[0028] Preferably, the purity of the metal element is ≥99.95wt.%, for example, it can be 99.95wt.%, 99.96wt.%, 99.97wt.%, 99.98wt.% or 99.99wt.%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the heating power applied for the vacuum induction melting is 0.7-1.0 kW, for example, 0.7 kW, 0.75 kW, 0.8 kW, 0.85 kW, 0.9 kW, 0.95 kW or 1 kW, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, before the vacuum induction melting, vacuuming and filling with a protective atmosphere are performed in sequence.

[0031] Preferably, the protective atmosphere comprises argon and / or nitrogen.

[0032] Preferably, a circular hole is arranged at the center of the microporous sheet.

[0033] Preferably, the diameter of the circular hole is 100-150 μm, for example, it can be 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm or 150 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In the present invention, the material of the microporous sheet can be a heat-resistant material commonly used in the art, for example, it can be any one of quartz, graphite, alumina or boron nitride or a combination of at least two of them. The position and number of the circular holes are set as required. Generally, the circular holes are controlled to be distributed in a ring shape at the center of the microporous sheet, and generally 5-25 holes are preferably set, for example, 5, 10, 15, 20 or 25, but not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the transmission device is driven by piezoelectric ceramics.

[0036] In the present invention, one end of the transmission device is connected to the piezoelectric ceramic by a thread, and the other end is connected to the transmission rod. The transmission rod can be made of high-temperature resistant materials commonly used in the art, such as any one of boron nitride, zirconium oxide or graphite, or a combination of at least two of them.

[0037] Preferably, the piezoelectric frequency is controlled to be 100-300 Hz during the disturbance, for example, it can be 100 Hz, 120 Hz, 140 Hz, 150 Hz, 160 Hz, 180 Hz, 200 Hz, 220 Hz, 240 Hz, 250 Hz, 260 Hz, 280 Hz or 300 Hz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] As a preferred technical solution of the third aspect of the present invention, the preparation method comprises the following steps:

[0039] (1) according to the mass percentage, the corresponding metal element (purity ≥ 99.95wt.%) is loaded into a crucible with a microporous sheet at the bottom (a circular hole with a diameter of 100-150μm is arranged at the center of the microporous sheet), and vacuuming and filling with a protective atmosphere are performed in sequence, and then the heating power is adjusted to 0.7-1.0kW for vacuum induction melting and heat preservation to obtain an alloy melt;

[0040] (2) placing a transmission device into the alloy melt obtained in step (1), wherein one end of the transmission device is connected to the piezoelectric ceramic via a thread, and the other end is connected to the transmission rod, and the piezoelectric frequency is selected to be 100-300 Hz, so that the braking force is transmitted to the end of the transmission rod, causing disturbance to the alloy melt at the microporous sheet, forcing the alloy melt to be squeezed out of the holes of the microporous sheet, and then solidified to obtain lead-based refrigeration alloy microspheres.

[0041] (3) Screening the lead-based refrigeration alloy microspheres obtained in step (2) to obtain lead-based refrigeration alloy microspheres with a target particle size of 150-500 μm.

[0042] In a fourth aspect, the present invention provides a use of the lead-based refrigeration alloy microspheres as described in the second aspect of the present invention, wherein the lead-based refrigeration alloy microspheres are used as cold storage materials.

[0043] The lead-based refrigeration alloy microspheres provided by the present invention have the advantages of high sphericity, narrow particle size distribution, smooth surface, etc., and have good mechanical strength and refrigeration effect, and can be used for cold storage materials, especially for cold storage materials at 20-77K.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The microalloyed lead-based refrigeration alloy provided by the present invention can increase the hardness of the lead-based refrigeration alloy to HV 100 by using the first alloying element and the second alloying element and controlling the addition amount thereof for microalloying. 0.05 It increases from about 10.0 to 14.0-16.0, and while refining the grains, improving plasticity and toughness and increasing hardness, it does not affect the specific heat of the material too much, effectively overcoming the defects of Pb spheres being soft and easy to deform, improving the maintenance-free performance of the low-temperature refrigerator, and having a good refrigeration effect.

[0046] (2) The lead-based refrigeration alloy microspheres provided by the present invention have the advantages of high sphericity, narrow particle size distribution, smooth surface and no satellite balls, and the yield of lead-based refrigeration alloy microspheres with a size of 150-500 μm under optimal conditions is ≥90wt.%, which can achieve good refrigeration effect while meeting the needs of continuous operation of the refrigerator, and is particularly suitable as a cold storage material at 20-77K.

[0047] (3) The present invention utilizes the piezoelectric properties of piezoelectric ceramics to propose a near-net-shape forming method, which only requires a simple modification of the vacuum induction furnace. The particle size of the microspheres can be controlled by controlling parameters such as the circular hole diameter of the microporous sheet, the piezoelectric frequency, and the heating power. The preparation process is simple and efficient, which solves the technical difficulties in the domestic industrial preparation of lead-based refrigeration alloy microspheres. It is also similarly applicable to the preparation of microspheres of single substances or their alloys such as Bi, Zn, Sn or Cu. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is an optical micrograph of the lead-based refrigeration alloy microspheres obtained in Example 1 of the present invention;

[0049] Figure 2 The XRD spectrum of the lead-based refrigeration alloy microspheres obtained in Example 2 of the present invention;

[0050] Figure 3 This is a comparison chart of the specific heat data of the lead-based refrigeration alloy microspheres obtained in Example 3 of the present invention and the single substance Pb in Comparative Example 3. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] In the following examples and comparative examples, a BZJ 200 type slap-type vibration screening machine was used to classify the lead-based refrigeration alloy microspheres;

[0053] The fluidity and bulk density of lead-based refrigeration alloy microspheres were tested using a BOS1002 Hall flow meter.

[0054] The tap density of lead-based refrigeration alloy microspheres was tested using a HY 100A tap density meter.

[0055] The Vickers hardness of lead-based refrigeration alloy was measured using MHVS-1000Z micro-Vickers hardness tester.

[0056] Example 1

[0057] The present embodiment provides a micro-alloyed lead-based refrigeration alloy, the lead-based refrigeration alloy comprising a main element Pb, a first alloying element and a second alloying element, the first alloying element being Sb, the second alloying element being a combination of Ag, Te and Cu, the lead-based refrigeration alloy comprising, by mass percentage, 4.40wt.% Sb, 0.10wt.% Ag, 0.10wt.% Cu and 0.10wt.% Te, wherein Ag, Cu and Te total 0.30wt.%, and the remainder being Pb, and the Vickers hardness is HV 0.05 It is 14.3±0.3.

[0058] This embodiment provides a lead-based refrigeration alloy microsphere, wherein the lead-based refrigeration alloy microsphere contains the above-mentioned micro-alloyed lead-based refrigeration alloy, and the lead-based refrigeration alloy microsphere is obtained by the following preparation method:

[0059] (1) According to the mass percentage, the corresponding metal element (purity ≥ 99.95wt.%) is loaded into a boron nitride crucible with a microporous sheet (made of boron nitride, with 10 circular holes with a diameter of 120 μm arranged in a ring shape at the center) at the bottom, with a total weight of 2000 g, and vacuuming and filling with protective atmosphere argon are performed in sequence, and then the heating power is adjusted to 0.9 kW for vacuum induction melting and heat preservation to obtain an alloy melt;

[0060] (2) placing a transmission device into the alloy melt obtained in step (1), wherein one end of the transmission device is connected to the piezoelectric ceramic via a thread, and the other end is connected to the transmission rod. The piezoelectric frequency is selected to be 150 Hz, so that the braking force is transmitted to the end of the transmission rod, causing disturbance to the alloy melt at the microporous sheet, forcing the alloy melt to be squeezed out of the holes of the microporous sheet, and then solidified to obtain lead-based refrigeration alloy microspheres. The ball making process takes about 4 hours.

[0061] (3) The lead-based refrigeration alloy microspheres obtained in step (2) are sieved to obtain lead-based refrigeration alloy microspheres with a target particle size of 150-500 μm, with a yield of 91.20 wt.%.

[0062] The lead-based refrigeration alloy microspheres in Example 1 were graded and weighed to calculate their particle size distribution. The results are shown in Table 1.

[0063] Table 1

[0064] Particle size Mass percentage / wt.% Particle size <100μm 3.44 Particle size 100-150μm 5.36 Particle size 150-200 μm 1.20 Particle size 200-250μm 17.79 Particle size 250-300μm 24.87 Particle size 300-350μm 23.90 Particle size 350-400μm 19.88 Particle size 400-450μm 3.56 Particle size 450-500μm 0 Particle size>500μm 0

[0065] Among them, the fluidity of lead-based refrigeration alloy microspheres with a particle size of 150-500μm is 2.41s / 50g, and the bulk density is 6.39g / cm 3 , tap density is 6.89g / cm 3 .

[0066] Taking Example 1 as an example, the optical micrograph of the obtained lead-based refrigeration alloy microspheres is as follows: Figure 1 As shown, from Figure 1 It can be seen that the obtained lead-based refrigeration alloy microspheres have high sphericity, uniform particle size distribution, no hollow powder and satellite balls, and the particle size is mainly distributed between 200-400 μm.

[0067] Example 2

[0068] The present embodiment provides a micro-alloyed lead-based refrigeration alloy, the lead-based refrigeration alloy comprising a main element Pb, a first alloying element and a second alloying element, the first alloying element being Sb, the second alloying element being a combination of Ag, Te and Cu, the lead-based refrigeration alloy comprising, by mass percentage, 4.50wt.% Sb, 0.30wt.% Ag, 0.20wt.% Cu and 0.10wt.% Te, wherein Ag, Cu and Te total 0.60wt.%, and the remainder being Pb, and the Vickers hardness is HV 0.05 It is 15.7±0.3.

[0069] This embodiment provides a lead-based refrigeration alloy microsphere, wherein the lead-based refrigeration alloy microsphere contains the above-mentioned micro-alloyed lead-based refrigeration alloy, and the lead-based refrigeration alloy microsphere is obtained by the following preparation method:

[0070] (1) According to the mass percentage, the corresponding metal element (purity ≥ 99.95wt.%) is loaded into a boron nitride crucible with a microporous sheet (made of alumina, with 15 circular holes with a diameter of 150 μm arranged in a ring shape at the center) at the bottom, with a total weight of 2000 g, and vacuuming and filling with protective atmosphere argon gas are performed in sequence, and then the heating power is adjusted to 0.7 kW for vacuum induction melting and heat preservation to obtain an alloy melt;

[0071] (2) placing a transmission device into the alloy melt obtained in step (1), wherein one end of the transmission device is connected to the piezoelectric ceramic via a thread, and the other end is connected to the transmission rod. The piezoelectric frequency is selected to be 200 Hz, so that the braking force is transmitted to the end of the transmission rod, causing disturbance to the alloy melt at the microporous sheet, forcing the alloy melt to be squeezed out of the holes of the microporous sheet, and then solidified to obtain lead-based refrigeration alloy microspheres. The ball making process takes about 2.5 hours.

[0072] (3) The lead-based refrigeration alloy microspheres obtained in step (2) are sieved to obtain lead-based refrigeration alloy microspheres with a target particle size of 150-500 μm, with a yield of 95.54 wt.%.

[0073] The lead-based refrigeration alloy microspheres in Example 2 were graded and weighed to calculate their particle size distribution. The results are shown in Table 2.

[0074] Table 2

[0075]

[0076]

[0077] Among them, the fluidity of lead-based refrigeration alloy microspheres with a particle size of 150-500μm is 2.33s / 50g, and the bulk density is 6.27g / cm 3 , tap density is 6.85g / cm 3 .

[0078] Taking Example 2 as an example, the obtained lead-based refrigeration alloy microspheres were subjected to XRD analysis, and the results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the lead-based refrigeration alloy microspheres have a two-phase structure, in which the main phase is the Pb phase and the second phase is the weaker Sb phase, with no other impurity peaks. This is because the second alloy element is doped in trace amounts.

[0079] Example 3

[0080] The present embodiment provides a micro-alloyed lead-based refrigeration alloy, the lead-based refrigeration alloy comprising a main element Pb, a first alloying element and a second alloying element, the first alloying element being Sb, the second alloying element being a combination of Ag, Te and Cu, the lead-based refrigeration alloy comprising, by mass percentage, 4.26wt.% Sb, 0.27wt.% Ag, 0.06wt.% Cu and 0.06wt.% Te, wherein Ag, Cu and Te total 0.39wt.%, and the remainder being Pb, and the Vickers hardness is HV 0.05 It is 14.7±0.3.

[0081] This embodiment provides a lead-based refrigeration alloy microsphere, wherein the lead-based refrigeration alloy microsphere contains the above-mentioned micro-alloyed lead-based refrigeration alloy, and the lead-based refrigeration alloy microsphere is obtained by the following preparation method:

[0082] (1) According to the mass percentage, the corresponding metal element (purity ≥ 99.95wt.%) is loaded into a boron nitride crucible with a microporous sheet (made of quartz, with 5 circular holes with a diameter of 100 μm arranged in a ring shape at the center) at the bottom, with a total weight of 2000 g, and vacuuming and filling with protective atmosphere argon gas are performed in sequence, and then the heating power is adjusted to 0.8 kW for vacuum induction melting and heat preservation to obtain an alloy melt;

[0083] (2) Place the transmission device into the alloy melt obtained in step (1), wherein one end of the transmission device is connected to the piezoelectric ceramic through a thread, and the other end is connected to the transmission rod. The piezoelectric frequency is selected to be 100 Hz, so that the braking force is transmitted to the end of the transmission rod, causing disturbance to the alloy melt at the microporous sheet, forcing the alloy melt to be squeezed out of the holes of the microporous sheet, and then solidified to obtain lead-based refrigeration alloy microspheres. The ball making process takes about 5 hours.

[0084] (3) The lead-based refrigeration alloy microspheres obtained in step (2) are sieved to obtain lead-based refrigeration alloy microspheres with a target particle size of 150-500 μm, with a yield of 92.20 wt.%.

[0085] The lead-based refrigeration alloy microspheres in Example 3 were graded and weighed to calculate their particle size distribution. The results are shown in Table 3.

[0086] Table 3

[0087] Particle size Mass percentage / wt.% Particle size <100μm 2.88 Particle size 100-150μm 4.92 Particle size 150-200 μm 29.99 Particle size 200-250μm 55.19 Particle size 250-300μm 1.90 Particle size 300-350μm 2.24 Particle size 350-400μm 2.88 Particle size 400-450μm 0 Particle size 450-500μm 0 Particle size>500μm 0

[0088] Among them, the fluidity of lead-based refrigeration alloy microspheres with a particle size of 150-500μm is 2.25s / 50g, and the bulk density is 6.60g / cm 3 , tap density is 7.20g / cm 3 .

[0089] Example 4

[0090] The present embodiment provides a micro-alloyed lead-based refrigeration alloy, the lead-based refrigeration alloy comprising a main element Pb, a first alloying element and a second alloying element, the first alloying element being Sb, the second alloying element being a combination of Ag, Te and Cu, the lead-based refrigeration alloy comprising, by mass percentage, 4.00wt.% Sb, 0.30wt.% Ag, 0.10wt.% Cu and 0.10wt.% Te, wherein Ag, Cu and Te total 0.50wt.%, and the remainder being Pb, and the Vickers hardness is HV 0.05 It is 14.4±0.3.

[0091] This embodiment provides a lead-based refrigeration alloy microsphere, wherein the lead-based refrigeration alloy microsphere contains the above-mentioned micro-alloyed lead-based refrigeration alloy, and the lead-based refrigeration alloy microsphere is obtained by the following preparation method:

[0092] (1) According to the mass percentage, the corresponding metal element (purity ≥ 99.95wt.%) is loaded into a boron nitride crucible with a microporous sheet (made of alumina, with 25 circular holes with a diameter of 100 μm arranged in a ring shape at the center) at the bottom, with a total weight of 2000 g, and vacuuming and filling with protective atmosphere argon gas are performed in sequence, and then the heating power is adjusted to 1.0 kW for vacuum induction melting and heat preservation to obtain an alloy melt;

[0093] (2) placing a transmission device into the alloy melt obtained in step (1), wherein one end of the transmission device is connected to the piezoelectric ceramic via a thread, and the other end is connected to the transmission rod, and the piezoelectric frequency is selected to be 300 Hz, so that the braking force is transmitted to the end of the transmission rod, causing disturbance to the alloy melt at the microporous sheet, forcing the alloy melt to be squeezed out of the holes of the microporous sheet, and then solidified to obtain lead-based refrigeration alloy microspheres. The ball making process takes about 1.5 hours.

[0094] (3) The lead-based refrigeration alloy microspheres obtained in step (2) are sieved to obtain lead-based refrigeration alloy microspheres with a target particle size of 150-500 μm, with a yield of 95.91 wt.%.

[0095] The lead-based refrigeration alloy microspheres in Example 4 were graded and weighed to calculate their particle size distribution. The results are shown in Table 4.

[0096] Table 4

[0097]

[0098]

[0099] Among them, the fluidity of lead-based refrigeration alloy microspheres with a particle size of 150-500μm is 2.10s / 50g, and the bulk density is 6.47g / cm 3 , tap density is 6.95g / cm 3 .

[0100] In the above Examples 1-4, the addition amount of the first alloying element is ≤4.5wt.%, and the addition amount of the second alloying element is ≤0.60wt.%. Since the addition amount of the first alloying element and the second alloying element is controlled to be very small in the present application, the volume specific heat capacity of the single substance Pb will hardly be affected too much. Taking Example 3 as an example, the specific heat data of the obtained lead-based refrigeration alloy microspheres are detected by using a comprehensive physical property measurement system (PPMS). Figure 3 As shown, from Figure 3 It can be seen that the obtained lead-based refrigeration alloy microspheres have a large volume specific heat capacity at low temperatures. At the same time, the hardness of the lead-based refrigeration alloy obtained in Examples 1-4 is HV 0.05 The hardness reaches above 14.3±0.3, which is significantly improved compared with metal Pb, effectively overcoming the defects of Pb sphere being soft and easy to deform.

[0101] Example 5

[0102] This embodiment provides a micro-alloyed lead-based refrigeration alloy. The only difference from the embodiment 1 is that the proportion of the second alloying element remains unchanged and is only Ag. The Vickers hardness is HV 0.05 It is 13.5±0.4.

[0103] Example 6

[0104] This embodiment provides a micro-alloyed lead-based refrigeration alloy. The only difference from the embodiment 1 is that the proportion of the second alloying element remains unchanged and is only Te. The Vickers hardness is HV 0.05 It is 12.8±0.5.

[0105] Example 7

[0106] This embodiment provides a micro-alloyed lead-based refrigeration alloy. The only difference from the embodiment 1 is that the proportion of the second alloying element remains unchanged and is only Cu. The Vickers hardness is HV 0.05 It is 13.1±0.3.

[0107] From the comparison between the above Examples 5-7 and Example 1, it can be seen that in Examples 5-7, compared with Example 1, the proportions of the first alloying element and the second alloying element remain unchanged, and therefore have almost no effect on the specific heat. From the aspect of hardness, it can be seen that the hardness in Example 1 is significantly better than that in Examples 5-7. It can be seen that the present invention can further improve the hardness of the alloy and enhance the wear resistance by preferentially controlling the second alloying element to adopt the three elements of Ag, Te and Cu to cooperate with each other.

[0108] Example 8

[0109] This embodiment provides a method for preparing lead-based refrigeration alloy microspheres. The only difference compared with Example 1 is that the heating power is 1.2 kW, and the yield of the obtained lead-based refrigeration alloy microspheres is 60.72 wt%.

[0110] Example 9

[0111] This embodiment provides a method for preparing lead-based refrigeration alloy microspheres. The only difference compared with Example 1 is that the piezoelectric frequency is 80 Hz, and the yield of the obtained lead-based refrigeration alloy microspheres is 32.59 wt%.

[0112] Example 10

[0113] This embodiment provides a method for preparing lead-based refrigeration alloy microspheres. The only difference compared with Example 1 is that the piezoelectric frequency is 350 Hz, and the yield of the obtained lead-based refrigeration alloy microspheres is 68.46 wt%.

[0114] Embodiment 11

[0115] This embodiment provides a method for preparing lead-based refrigeration alloy microspheres. The only difference from the method in Embodiment 1 is that the diameter of the circular hole is 180 μm, and the yield of the obtained lead-based refrigeration alloy microspheres is 28.62 wt %.

[0116] From the comparison between the above Examples 8-11 and Example 1, it can be seen that the present invention can regulate the particle size of the microspheres by preferentially controlling parameters such as the heating power, the piezoelectric frequency and the diameter of the circular hole, thereby further improving the yield of lead-based refrigeration alloy microspheres within the particle size range that meets commercial requirements (150-500 μm).

[0117] Comparative Example 1

[0118] This comparative example provides a lead-based refrigeration alloy, which is different from Example 1 only in that the proportion of the first alloying element is kept unchanged and the second alloying element is not added;

[0119] That is, the lead-based refrigeration alloy includes 4.0wt.% Sb and the remainder is Pb, and the Vickers hardness is HV 0.05 It is 11.4±0.5.

[0120] Comparative Example 2

[0121] This comparative example provides a lead-based refrigeration alloy, which is different from Example 1 only in that the proportion of the second alloying element is kept unchanged and the first alloying element is not added;

[0122] That is, the lead-based refrigeration alloy includes 0.30wt.% Ag, 0.20wt.% Cu and 0.10wt.% Te, and the balance is Pb. The Vickers hardness is HV 0.05 It is 11.0±0.5.

[0123] From the comparison between the above comparative examples 1-2 and example 1, it can be seen that the hardness in example 1 is significantly better than that in comparative examples 1-2. It can be seen that the present invention can effectively increase the hardness and improve the wear resistance of the alloy by simultaneously adding the first alloying element and the second alloying element.

[0124] Comparative Example 3

[0125] This comparative example provides a cold storage material, which is a single substance Pb with a Vickers hardness of HV 0.05 is about 10.0. The specific heat capacity data of single substance Pb in this comparative example are as follows Figure 3 As shown, the data comes from the journal Materials Today: Proceedings 4 (2017) 5544-5551.

[0126] From the comparison between the comparative example 3 and the example 3, it can be seen that the hardness in the example 3 is obviously better than that in the comparative example 3. It can be seen that the lead-based refrigeration alloy provided by the present invention can effectively improve the hardness compared with the single substance Pb, and the specific heat data of the example 3 and the comparative example 3 are compared. Figure 3 As shown, from Figure 3 It can be seen that the specific heat capacity of the lead-based refrigeration alloy provided by the present invention is not much reduced compared with that of the single substance Pb, and still maintains a relatively large value, which further illustrates that the present invention can improve the hardness while avoiding excessive influence on the specific heat of the material through the controlled addition of the first alloying element and the second alloying element, and is suitable for cold storage materials in commercial refrigerators.

[0127] In summary, the present invention reduces the amount of alloying elements through multi-component microalloying, while refining the grains, improving plasticity and toughness, and increasing hardness without excessively affecting the specific heat of the material. The preparation process is simple and efficient, which is conducive to industrial production.

[0128] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A microalloyed lead-based refrigeration alloy, It is characterized in that The lead-based refrigeration alloy comprises a main element Pb, a first alloying element and a second alloying element; The first alloying element includes Sb; The second alloying element includes any one of Ag, Te or Cu or a combination of at least two thereof; The lead-based refrigeration alloy comprises, by mass percentage, 4.0-4.5wt.% of a first alloying element, 0.30-0.60wt.% of a second alloying element, and the remainder is Pb.

2. The lead-based refrigeration alloy according to claim 1, It is characterized in that The Vickers hardness of the lead-based refrigeration alloy is HV 0.05 It is 14.0-16.

0.

3. The lead-based refrigeration alloy according to claim 1 or 2, It is characterized in that The second alloying elements include, by mass percentage, 0.10-0.30 wt. % of Ag, 0.06-0.20 wt. % of Cu and 0.06-0.10 wt. % of Te.

4. A lead-based refrigeration alloy microsphere, It is characterized in that The lead-based refrigeration alloy microspheres contain the microalloyed lead-based refrigeration alloy as described in any one of claims 1-3.

5. The lead-based refrigeration alloy microsphere according to claim 4, It is characterized in that The particle size of the lead-based refrigeration alloy microspheres is 150-500 μm; Preferably, the fluidity of the lead-based refrigeration alloy microspheres is (2.10-2.41) s / 50g; Preferably, the bulk density of the lead-based refrigeration alloy microspheres is 6.27-6.60 g / cm 3 ; Preferably, the tap density of the lead-based refrigeration alloy microspheres is 6.85-7.20 g / cm 3 .

6. A method for preparing the lead-based refrigeration alloy microspheres as claimed in claim 4 or 5, It is characterized in that The preparation method comprises the following steps: (1) charging corresponding metal elements into a crucible with a microporous sheet at the bottom according to the mass percentage, and then performing vacuum induction melting to obtain an alloy melt; (2) placing a transmission device into the alloy melt obtained in step (1), disturbing the alloy melt at the microporous sheet through the transmission device, forcing the alloy melt to be squeezed out from the holes of the microporous sheet, and then solidifying to obtain lead-based refrigeration alloy microspheres.

7. The preparation method according to claim 6, It is characterized in that The preparation method further comprises step (3): screening the lead-based refrigeration alloy microspheres obtained in step (2) to obtain lead-based refrigeration alloy microspheres of target particle size.

8. The preparation method according to claim 6 or 7, It is characterized in that The purity of the metal element is ≥99.95wt.%.

9. The preparation method according to any one of claims 6 to 8, It is characterized in that The heating power applied by the vacuum induction melting is 0.7-1.0kW; Preferably, before the vacuum induction melting, vacuuming and filling with a protective atmosphere are sequentially performed; Preferably, the protective atmosphere comprises argon and / or nitrogen; Preferably, a circular hole is arranged at the center of the microporous sheet; Preferably, the diameter of the circular hole is 100-150 μm; Preferably, the transmission device is driven by piezoelectric ceramics; Preferably, the piezoelectric frequency is controlled to be 100-300 Hz during the disturbance.

10. Use of the lead-based refrigeration alloy microspheres as claimed in claim 4 or 5, It is characterized in that The lead-based refrigeration alloy microspheres are used as cold storage materials.

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