CN115404368B

CN115404368B - Preparation method of low-melting-point tin-base alloy

Info

Publication number: CN115404368B
Application number: CN202211046371.4A
Authority: CN
Inventors: 顾立立; 刘慧科
Original assignee: SUNRISE GROUP CO Ltd
Current assignee: SUNRISE GROUP CO Ltd
Priority date: 2022-08-30
Filing date: 2022-08-30
Publication date: 2023-10-10
Anticipated expiration: 2042-08-30
Also published as: CN115404368A

Abstract

The application discloses a preparation method of a low-melting-point tin-base alloy, which comprises the following smelting steps: preheating a container in a heating furnace at 1000-2000 ℃ for 20-60min, adding doped metal into the container, and adding tin into the container after the doped metal is completely melted to obtain an alloy solution; in the alloy solution, the mass fraction of the doped metal is 0.1% -50%, and the mass fraction of the tin is 50% -99.9%. The preparation method has the characteristics of short smelting time and small oxidation degree of the alloy, and the prepared alloy has the characteristics of low melting point and conductivity.

Description

Preparation method of low-melting-point tin-base alloy

Technical Field

The application relates to an alloy preparation method, in particular to a preparation method of a low-melting-point tin-based alloy.

Background

The low-melting-point alloy is a metal material with development potential and is widely applied to various fields: the anti-radiation special stop block can be used for making a special anti-radiation stop block in a specific shape in medical treatment; in production, the mold can be conveniently used as a casting mold for producing special products; in the field of electronic and electric automatic control, the material is widely used for manufacturing thermosensitive elements, safety materials, fire alarm devices and the like.

Lead is generally added to obtain an alloy with a lower melting point, but because of the extremely toxic nature of lead and its compounds, incurs incurable harm to human health and living environment, the call for prohibiting the use of lead-containing alloys in electronic products and various production fields is increasingly rising, and people focus on the research of tin-based alloys. The tin-base alloy has moderate hardness, better toughness, good corrosion resistance and thermal conductivity, and can be applied to various industries by simply adjusting the melting point and wettability by adding other metal elements.

At present, the manufacturing process of the low-melting-point alloy generally melts the metal with the lowest low melting point under the condition of lower than 300 ℃, and then adds the metal from low melting point to high melting point according to the pure metal or melts the metal from high to low according to the proportion of raw materials.

Disclosure of Invention

The application aims to provide a preparation method of a low-melting-point tin-base alloy with short smelting time and small oxidation degree.

Another object of the present application is to provide a temperature protection element that has a low melting point and is electrically conductive.

In order to achieve the above purpose, the application adopts the following technical scheme: the preparation method of the low-melting-point tin-base alloy comprises the following smelting steps: preheating a container in a heating furnace at 1000-2000 ℃ for 20-60min, adding doped metal into the container, and adding tin into the container after the doped metal is completely melted to obtain an alloy solution; in the alloy solution, the mass fraction of the doped metal is 0.1-50%, and the mass fraction of the tin is 50-99.9%.

Preferably, the doping metal is selected from one or two of copper and silver.

As another preferable, the mass fraction of the doping metal is 2% -10%, and the mass fraction of the tin is 90% -98%.

As another preferred, the doping metal includes copper and silver, wherein the mass fraction of copper is 2% -6%, the mass fraction of silver is 2% -6%, and the mass fraction of tin is in the range of 88% -96%.

As another preferable aspect, the doping metal includes copper and silver, and in the smelting step, the silver is added to the container first, the copper is added after the silver is completely melted, and the tin is added to the container after the copper is completely melted, so as to obtain the alloy solution.

As another preferable, the temperature range of the heating furnace is selected from 1000-1200 ℃.

As another preferred, the smelting step is followed by a degassing step, an ingot casting step, a cooling step and a polishing step:

and (3) degassing: clamping the container after no slag exists on the surface of the alloy solution, fully stirring the container by using a carbon rod, putting a reducing agent on the container to reduce and degas the alloy solution, and stirring the container again after complete reduction to ensure that the surface of the alloy solution is clear and free of impurities, thus obtaining reduced alloy solution;

ingot casting: pouring the reduced alloy solution into a pre-cleaned ingot mould, and then sealing the ingot mould to avoid oxidation of the alloy in the cooling process;

and (3) a cooling step: opening the ingot mould after cooling for 15-20min to obtain a solid alloy;

polishing: cleaning and grinding the surface of the solid alloy to remove an oxide layer on the surface of the solid alloy; and performing subsequent cleaning work.

As another preferred aspect, the smelting step is preceded by a preparation step of:

the preparation steps are as follows: preparing Sn with the purity of 99.99 percent, the doped metal raw material and a refining agent; the refining agent is a phosphorus-containing refining agent.

As another preference, the reducing agent used in the degassing step is rosin.

A temperature protection element is provided, and the temperature protection element is manufactured by using the preparation method.

Compared with the prior art, the application has the beneficial effects that:

(1) By changing the smelting temperature and adding the doped metal for smelting, the smelting time is effectively shortened, and the preparation efficiency of the tin-base alloy is improved;

(2) By shortening the smelting time, the contact oxidation time of the alloy and air is reduced, so that the oxidation degree of the alloy is reduced;

(3) The alloy obtained by the preparation method has low fusing temperature, can conduct electricity and is suitable for being used as a temperature protection element.

Drawings

FIG. 1 is a process flow diagram of the present application;

FIG. 2 is a DSC analysis chart of the present application in example 1 and example 2.

FIG. 3 is a DSC analysis chart of the present application in example 4 and example 5.

Detailed Description

The present application will be further described with reference to the following specific embodiments, and it should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below.

The terms "comprises" and "comprising," along with any variations thereof, in the description and claims, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The low-melting-point alloy of the base Yu Xiji is a metal alloy with moderate hardness and better toughness, and the melting point and wettability of the metal alloy can be easily adjusted by adding other metal elements, so that the metal alloy is considered to be one of lead-free materials most likely to replace tin-lead alloy, and is suitable for being widely applied to various industries. The current preparation process of the tin-based low-melting-point alloy generally comprises the steps of firstly melting metal tin with a lower melting point in alloy components at a melting temperature lower than 300 ℃, then adding other alloy components in steps, and then conventionally carrying out degassing and ingot casting steps to obtain the tin-based low-melting-point alloy. In the synthesis process, the smelting temperature is lower, and the metal component with high melting point needs longer smelting time, so that the time for the alloy to contact with air is prolonged, and the oxidation degree of the alloy is deepened; and tin is used as a component for melting at the earliest time and the melting point is lower than the melting temperature, so that tin element volatilizes, material loss is increased, and resource waste is caused.

The application provides a preparation method of a low-melting-point tin-base alloy, which has short smelting time and small oxidation degree of the alloy, wherein the preparation flow is shown in figure 1 and comprises a preparation step, a smelting step, a degassing step, an ingot casting step, a cooling step and a polishing step.

The preparation steps are as follows: preparing Sn, a doped metal raw material and a refining agent, wherein the doped metal is selected from one or two of Ag and Cu, and the refining agent;

smelting: the temperature range of the heating furnace is set to be 1000-2000 ℃, after the heating furnace reaches the preset temperature, the crucible is placed in the heating furnace to be preheated for 20-60min, doped metal is added first, after the doped metal alloy is completely melted, sn is added into the crucible to obtain alloy solution, and the mass fraction of the doped metal in the alloy solution is selected from 0.1% -50%, and the mass fraction of the Sn is 50% -99.9%;

and (3) degassing: clamping a crucible out after no slag exists on the surface of the alloy solution, fully stirring the crucible by using a carbon rod, putting a reducing agent on the crucible to reduce and degas the alloy solution, and stirring the crucible again after complete reduction to ensure that the surface of the solution is clear and free of impurities, thus obtaining reduced alloy solution;

and (3) a cooling step: after the ingot mould is cooled for 15-20min, the sealing mould can be opened to obtain solid alloy;

polishing: cleaning and grinding the cooled solid alloy surface to remove an oxide layer on the surface; and performing subsequent cleaning work.

In some embodiments, the doped metal component added in the smelting step may be a doped copper component, a doped silver component, or a doped copper-silver alloy component.

In some embodiments, the mass fraction of the doping metal is set to a range of 2% -10% and the mass fraction of the tin-based is set to a range of 90% -98%.

In some embodiments, in the step of melting the tin-based alloy doped with copper and silver, cu may be melted first and then Ag may be melted, or Ag may be melted first and then Cu may be melted, and then the doped metal alloy may be obtained.

In some embodiments, the temperature of the furnace is selected from the range of 1000-1200 ℃.

In some preferred embodiments, the preheat time is set to 30 minutes.

In some embodiments, 0.1wt% refining agent is added during the smelting step, the refining agent being used to remove insoluble impurities in the smelting.

In some embodiments, the starting materials in the preparing step are preferably Sn, cu, and Ag having a purity of 99.99%, and the refining agent is preferably a phosphorus-containing refining agent.

In some embodiments, the reducing agent used in the degassing step may be carbon monoxide gas, hydrogen gas, rosin, or the like.

In some embodiments, the ingot mold may be rectangular parallelepiped, cylindrical, triangular pyramid, etc. in shape.

In some embodiments, the alloys prepared by the present application can be used as temperature protection elements such as fuses, fire alarms, etc. using their lower fusing temperatures.

In the following, specific examples of the present application are described in which raw materials, equipment and the like used are obtained by purchasing them except for specific limitations.

Example 1:

Cu _0.1 -Sn _0.9 the alloy comprises the following components in percentage by weight: 10%, the balance being Sn.

The preparation steps are as follows: preparing Sn and Cu raw materials with the purity of 99.99 percent and 0.1 weight percent of phosphorus-containing refining agent;

smelting: setting the temperature of a heating furnace to 1200 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Cu, starting timing while adding Cu, adding Sn into the crucible after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T1; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution;

and (3) degassing: clamping a crucible out after no slag exists on the surface of the alloy solution, fully stirring the crucible by using a carbon rod, putting rosin on the crucible to reduce and degas the alloy solution, and stirring the crucible again after black smoke generated by covering the rosin is completely removed to ensure that the surface of the solution is clear and free of impurities, thus obtaining reduced alloy solution;

ingot casting: pouring the reduced alloy solution into a pre-cleaned cylindrical ingot mould, and then sealing the ingot mould to avoid oxidation of the alloy in the cooling process;

and (3) a cooling step: after the ingot mould is cooled for 15-20min, the sealing mould can be opened to obtain the cylindrical tin-based low-melting-point alloy with the length of 220mm and the diameter of about 35mm, the weight of the alloy is about 1kg, and the alloy contains trace phosphorus elements.

Polishing: cleaning and grinding the surface of the cooled tin-based low-melting-point alloy to remove an oxide layer on the surface of the alloy; and performing subsequent cleaning operations such as cleaning the mold, cleaning the inner wall of the heating furnace, inspecting the electronic control elements of the heating furnace, heating the carbon rod, and the like.

Comparative example 1:

Cu _0.1 -Sn _0.9 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing while adding Sn, adding Cu into the crucible after the Sn is completely melted, and stopping timing after the Cu is completely melted to obtain time t1; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 2:

Cu _0.06 -Sn _0.94 the alloy comprises the following components in percentage by weight: 6, the balance of Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1200 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Cu, starting timing while adding Cu, adding Sn into the crucible after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T2; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 2:

Cu _0.06 -Sn _0.94 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 2;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing while adding Sn, adding Cu into the crucible after the Sn is completely melted, and stopping timing after the Cu is completely melted to obtain time t2; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 3:

Cu _0.02 -Sn _0.98 the alloy comprises the following components in percentage by weight: 2%, the balance being Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1200 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Cu, starting timing while adding Cu, adding Sn into the crucible after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T3; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 3:

Cu _0.02 -Sn _0.98 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 3;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing while adding Sn, adding Cu into the crucible after the Sn is completely melted, and stopping timing after the Cu is completely melted to obtain time t3; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 4:

Ag _0.1 -Sn _0.9 the alloy comprises the following components in percentage by weight: 10%, the balance being Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Sn into the crucible after the Ag is completely melted, and stopping timing after the Sn is completely melted to obtain time T4; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 4:

Ag _0.1 -Sn _0.9 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 4;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing while adding Sn, adding Ag into the crucible after the Sn is completely melted, and stopping timing after the Ag is completely melted to obtain time t4; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 5:

Ag _0.06 -Sn _0.94 the alloy comprises the following components in percentage by weight: 6, the balance of Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Sn into the crucible after the Ag is completely melted, and stopping timing after the Sn is completely melted to obtain time T5; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 5:

Ag _0.06 -Sn _0.94 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 5;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing while adding Sn, adding Ag into the crucible after the Sn is completely melted, and stopping timing after the Ag is completely melted to obtain time t5; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 6:

Ag _0.02 -Sn _0.98 the alloy comprises the following components in percentage by weight: 2%, the balance being Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Sn into the crucible after the Ag is completely melted, and stopping timing after the Sn is completely melted to obtain time T6; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 6:

Ag _0.02 -Sn _0.98 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 6;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing while adding Sn, adding Ag into the crucible after the Sn is completely melted, and stopping timing after the Ag is completely melted to obtain time t6; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 7:

Cu _0.02 -Ag _0.02 -Sn _0.96 the alloy comprises the following components in percentage by weight: 2%, ag:2%, the balance being Sn; the preparation process comprises the following preparation steps,The degassing step, the ingot casting step, the cooling step and the polishing step are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Cu into the crucible after the Ag is completely melted, adding Sn after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T7; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 7:

Cu _0.02 -Ag _0.02 -Sn _0.96 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 7;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing at the same time, adding Ag into the crucible after the Sn is completely melted, adding Cu after the Ag is completely melted, and stopping timing after the Cu is completely melted to obtain time t7; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 8:

Cu _0.06 -Ag _0.02 -Sn _0.92 the alloy comprises the following components in percentage by weight: 6%, ag:2%, the balance being Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Cu into the crucible after the Ag is completely melted, adding Sn after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T8; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 8:

Cu _0.06 -Ag _0.02 -Sn _0.92 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 8;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing at the same time, adding Ag into the crucible after the Sn is completely melted, adding Cu after the Ag is completely melted, and stopping timing after the Cu is completely melted to obtain time t8; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 9:

Cu _0.02 -Ag _0.06 -Sn _0.92 the alloy comprises the following components in percentage by weight: 2%, ag:6, the balance of Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Cu into the crucible after the Ag is completely melted, adding Sn after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T9; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 9:

Cu _0.02 -Ag _0.06 -Sn _0.92 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 9;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing at the same time, adding Ag into the crucible after the Sn is completely melted, adding Cu after the Ag is completely melted, and stopping timing after the Cu is completely melted to obtain time t9; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 10:

Cu _0.05 -Ag _0.05 -Sn _0.90 the alloy comprises the following components in percentage by weight: 5%, ag:5%, the balance being Sn; the preparation step, the degassing step, the ingot casting step, the cooling step and the polishing step of the preparation process are consistent with the scheme of the embodiment 1;

smelting: setting the temperature of a heating furnace to 1000 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Ag, starting timing while adding Ag, adding Cu into the crucible after the Ag is completely melted, adding Sn after the Cu is completely melted, and stopping timing after the Sn is completely melted to obtain time T10; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Comparative example 10:

Cu _0.05 -Ag _0.05 -Sn _0.90 the preparation step, degassing step, ingot casting step, cooling step and polishing step of the preparation process of the low-melting-point alloy are consistent with the scheme of the embodiment 10;

smelting: setting the temperature of a heating furnace to 350 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Sn, starting timing at the same time, adding Ag into the crucible after the Sn is completely melted, adding Cu after the Ag is completely melted, and stopping timing after the Cu is completely melted to obtain time t10; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Example 11:

smelting: setting the temperature of a heating furnace to 1200 ℃, preheating a crucible in the heating furnace for 30min after the heating furnace reaches the preset temperature, adding Cu, starting timing while adding Cu, adding Ag into the crucible after Cu is completely melted, adding Sn after Ag is completely melted, and stopping timing after Sn is completely melted to obtain time T11; if a small amount of impurities float on the top end of the solution, adding a small amount of refining agent for mixing to obtain alloy solution.

Performance detection

Alloy fusing temperature test: the alloy prepared in each example was connected to a 0.1A current, and the temperature of the alloy was measured as the alloy fusing temperature by connecting the alloy to an oil bath having a heating rate of 0.5 ℃/min.

Alloy conductivity test: the Sigma2008 digital eddy current metal conductivity meter is used for conducting conductivity test on the obtained low-melting-point alloy, and the meter is simple and convenient to use and can display important parameters such as test results, test frequency and temperature. Before the conductivity of the alloy is measured by using a digital eddy current metal conductivity meter, preparing a tested alloy sample, firstly, manufacturing the alloy into square blocks with the thickness of 5mm, and polishing to enable the surface of the alloy sample to be flat and smooth; and then calibrating the digital eddy current metal conductivity meter, and measuring the conductivity of the sample alloy material.

DSC analysis: and (3) adopting a differential scanning calorimetry (Differential Scanning Calorimetry, DSC for short), and enabling the sample to be under the control of a certain temperature program (temperature rise/temperature reduction/constant temperature), and observing the change process of the heat flow power difference of the sample end and the reference end along with the temperature or time, so as to obtain the heat effect information related to the heat absorption, the heat release, the specific heat change and the like of the sample in the temperature program process. The method comprises the following specific steps: the crucible with the sample and the reference crucible are placed on a sensor disc, thermal symmetry is maintained between the crucible and the reference crucible, the temperature is tested in a uniform furnace body according to a certain temperature program (linear temperature rise, temperature reduction, constant temperature and combination thereof), and a pair of thermocouples (reference thermocouple, sample thermocouple) is used for continuously measuring the temperature difference signals between the two. Because the heating process of the furnace body to the sample/reference product meets the Fourier heat conduction equation, the heating heat flow difference at the two ends is in proportion to the temperature difference signal, the original temperature difference signal can be converted into the heat flow difference signal through heat flow correction, and the time/temperature is continuously plotted to obtain a DSC spectrum with the ordinate representing the heat absorption and release speed of the alloy sample and the abscissa representing the time or the temperature.

X-ray energy spectrum analysis (EDS): and grinding the sample to be analyzed by adopting a QUANTAX type X-ray energy spectrometer (EDS), directly adhering the sample to be analyzed on a double-sided carbon adhesive, putting the sample into a sample bin without metal spraying, and carrying out energy spectrum analysis on the sample by adopting a high vacuum mode to carry out oxygen element content analysis.

And (3) effect analysis:

in the embodiment, the doped metal is melted first, and Sn is melted after the doped metal is completely melted; in the comparative example, the reverse melting sequence was adopted, in which Sn was melted first and then the doped metal component was melted. The time of the melting step of each of examples and comparative examples was measured and the time consumed was analyzed and the results are shown in Table 1.

Table 1: component content and melting step test time of each example and comparative example

As shown in Table 1, according to the melting steps and test time analysis of examples 1-3, at the melting temperature selected to be higher than the melting point of Cu, the melting step melts Cu first and then melts Sn, the Cu content is selected to be 2% -10%, and the required melting time is reduced as the Cu content of the component in the tin-copper alloy is reduced. Meanwhile, according to the melting steps and the test time analysis of the comparative examples 1-3, under the condition that the melting temperature is only higher than the melting point temperature of the component Sn, the melting step is designed to melt Sn and then Cu, and the time required for melting gradually decreases along with the reduction of the content of the copper component in the tin-copper alloy. The test time differences of example 1 and comparative example 1, example 2 and comparative example 2, and example 3 and comparative example 3 were calculated, respectively, the time required for the melting steps of comparative examples 1 to 3 was all longer than that of the corresponding examples 1 to 3, and the time difference of the comparative examples and the corresponding examples was gradually increased as the Cu content of the alloy component was increased. In the case of Cu content of 2%, the time required for comparative example 3 was even more than 1.5 times that required for example 3. Therefore, when preparing the tin-copper alloy, the smelting temperature is higher than the melting point of metal Cu, and the metal adding sequence melts Cu and then melts Sn, so that the smelting time is shortened, the contact time of the alloy and air is reduced, and the oxidation degree of the metal can be effectively reduced.

It was observed that the melting time T1 of example 1 and the melting time T2 of example 2 reduced from 374s to 182s when the Cu content was reduced from 10% to 6%, and an abnormal steep rise was observed in the melting time T1 of example 1. DSC analysis was performed on the two gold combinations of example 1 and example 2, as shown in fig. 2, in which a solid-liquid coexisting region exists between solidus and liquidus for the alloy, and in this region, solid phase particles are dispersed and in a liquid phase state, having properties like a liquid phase. The solid-liquid coexisting region shown in the DSC curve of the alloy prepared in example 1 is a-b-c, and a slow climbing appears obviously in the b-c stage, so that the melting time of the alloy is increased; in contrast, the DSC curve of the alloy prepared in example 2 shows that the solid-liquid coexisting region is f-g-h, and there is no gentle rise. Thus, it is presumed that when the Cu content is 10%, the melting time is also affected by the solid-liquid coexisting state of the metal, and the operating time is increased. Further, the alloy prepared in example 1 was found to have a wide melting temperature range by DSC analysis, and when applied to a thermal fuse, the alloy took a long time from reaching the melting point to completely fusing, which was disadvantageous for use as a temperature control element. Thus, in ternary alloy preparation, the Cu content was chosen to start from 6%.

According to the melting steps and test time analysis of examples 4-6, in the melting step of the silver-tin alloy, a temperature higher than the melting point of Ag is selected, ag is melted first and Sn is melted again, the content of Ag is selected to be 2% -10%, and the required melting time is gradually reduced along with the reduction of the content of Ag in the silver-tin alloy. According to the melting steps and test time analysis of comparative examples 4 to 6, the melting temperature was set to a temperature only higher than the melting point of Sn in the synthesis step, and then Sn was melted first and Ag was melted. With the progressive decrease in the content of the component Ag in comparative examples 4 to 6, the required melting time was simultaneously progressively decreased, but was higher than that required for the corresponding examples. In example 6 and comparative example 6, the content of the component Ag in the silver-tin alloy was only 2%, but the time of T6 versus T6 was shortened by about 65%, so that melting Ag first was advantageous for shortening the melting time.

It was observed that the same law as Cu appears at an Ag content of 10% in the melting time of the silver-tin alloy, and that analysis examples 4 and 5 reduced the silver content only from 10% to 6% and from 350s to 161s. DSC analysis is also carried out on the two combined gold of the example 4 and the example 5, as shown in FIG. 3, the solid-liquid coexisting region shown in the alloy DSC curve prepared in the example 4 is in the range of A-B-C, the solid-liquid coexisting region shown in the alloy DSC curve prepared in the example 5 is F-G-H, and the obvious B-C stage has a slow enthalpy change, so that the required smelting time is larger when the Ag content is 10%, and the operation range of the alloy temperature obtained by smelting is wider, which is unfavorable for being used as a temperature insurance element. Similarly, in the preparation of ternary alloys, the Ag content is selected to be in the range of 2% -6%. 1

According to the smelting steps of the copper-silver-tin ternary alloy of the embodiments 7-10, the smelting temperature is selected to be higher than the highest melting point temperature of the metal components, other metal components except Sn are firstly melted in the smelting step to obtain the doped metal alloy, and then the doped metal alloy is smelted with a tin base, wherein the content of Cu is selected to be 2% -6%, the content of Ag is selected to be 2% -6%, and the balance is Sn. Analysis example 7 and 10, when the Cu and Ag contents in the alloy are the same, the required melting time increases as the Sn content decreases. Analysis examples 8 and 9, in which the Sn content was the same in both examples, showed that the melting time required increased with increasing Cu content, and the effect of Cu content on melting time was greater than that of Ag.

In order to investigate the addition order of the doping components Cu and Ag in the tin-based alloy doped with copper and silver at the same time, examples 10 and 11 in which the Cu and Ag contents were the same but the melting order was different were set. As can be seen from the analysis of the results of T10 and T11, when preparing the doped metal alloy, the melting time required for melting Ag and then Cu is shorter, because the melting points of Ag and Cu are not different much, in this context, ag having a slightly lower melting point is melted first, and then Cu is melted into Ag liquid, so that the melting time can be saved.

The smelting time and the smelting temperature have influence on the purity of the prepared alloy, and the reaction of metal and oxygen is aggravated by the increase of the smelting time and the increase of the smelting temperature, so that metal oxides are more easily formed and doped in the prepared alloy, and the purity of the alloy is reduced. It is therefore necessary to compare the oxygen atom content in each example with that in each comparative example to evaluate the purity of the synthesized alloy. EDS analysis was performed on the alloys prepared in examples 1 to 11 and comparative examples 1 to 11, three test surfaces were taken for each sample to obtain data of three groups of oxygen atom contents of one sample, and the average value of the three groups of data was taken to obtain Table 2.

Table 2: results of EDS analysis of oxygen atom content of examples and comparative examples

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As can be seen from table 2, the average oxygen atom content in each comparative example was greater than that in the corresponding example, and it can be inferred that: the degree of oxidation of the alloy prepared in each comparative example was higher than that of the alloy in each corresponding example. Namely, the preparation method of melting the doped alloy at high temperature and then melting Sn saves time, and can reduce the oxidation of the alloy by air to obtain the alloy with higher purity. Analysis of examples 1-3 and examples 4-6, respectively, showed a positive correlation of the extent to which the alloy was oxidized with the melting time, and it was found that in alloy melting, the melting time mainly affected the purity of the alloy.

Analysis of the average oxygen atom content of examples 10 and 11 shows that in the step of preparing an alloy in which copper and silver are doped simultaneously, the alloy prepared by the scheme of smelting Ag and then smelting Cu, in which the average oxygen atom content is smaller, is oxidized to a lower extent. Thus, in the preparation scheme of the tin-based alloy doped with copper and silver, the preferable smelting sequence is to melt Ag first and then melt Cu, so that the oxidation degree of the alloy can be reduced.

The alloys prepared in examples 1 to 11 were subjected to a melting temperature test and a conductivity test to judge the conditions necessary for their use as temperature protective elements, and the test results are recorded in the following table 3.

Table 3: alloy fusing temperature and conductivity results for various examples

As can be seen from Table 3, in the test results of examples 1-3, as the Cu content of the component was reduced, the fusing temperature of the alloy was reduced from 289 ℃ to 226 ℃, and the conductivity of the alloy was gradually reduced. In the test results of examples 4 to 6, as the content of Ag in the component was reduced, the fusing temperature of the alloy was gradually lowered from 261 to 207℃and the conductivity thereof was gradually lowered; as can be seen from comparison of examples 1 and 4, examples 2 and 5, and examples 3 and 6, respectively, when Cu or Ag having the same tin-based doping content is doped, the fusing temperature and conductivity of the silver-tin alloy are lower than those of the copper-tin alloy.

The test results of examples 7-10 were observed to show that in the copper-silver-tin ternary alloys, both the alloy fusing temperature and the conductivity were lower than in the binary silver-tin alloys or copper-tin alloys. As is clear from examples 7 and 10, the larger the doping amount, the lower the alloy fusing temperature and conductivity, with the same doping metal ratio. As is clear from examples 8 and 9, the melting temperature and the conductivity of the alloy are positively correlated with the Cu content in the alloy components at the same tin-based content.

The results of the tests of examples 10-11 were observed, and although the alloy had consistent composition, the alloy produced in example 11 had different melting temperatures and conductivities, both lower than the alloy produced in example 10, and the analysis was due to the different melting order of Cu and Ag, resulting in different ratios of oxides in the two alloys, which in turn had an effect on the melting temperatures and conductivities. The preferred alloy is still prepared by melting Ag and then Cu in the order of melting.

In the application, the influence of smelting temperatures of copper doped tin base alloy, silver doped tin base alloy and smelting sequence of metal components on time is researched, and the screening of Cu and Ag contents of the components and the testing of fusing temperatures and electric conductivity of the alloy prepared by each embodiment are carried out, so that the conclusion is that: the smelting temperature is selected to be higher than the melting point temperature of the highest component, the doped metal is firstly melted and then fused with the tin base, so that the time required by smelting is shortened, the sufficient fusion of materials is facilitated, the contact time of an alloy solution and air is reduced, and the degree of oxidation of the metal is greatly reduced; cu and Ag are used as doped metal components, and the content of the Cu and Ag is lower than 10 percent, so that the smelting time is reduced; in the smelting step of the ternary alloy of copper, silver and tin, cu is melted after Ag is melted preferentially to prepare the doped metal alloy, so that the smelting time is shortened, and the oxidation degree of the doped metal alloy is reduced.

The tin-base alloy prepared by the method has lower fusing temperature and better conductivity, can be used as a temperature sensing element, a temperature fuse and the like in the field of fire control, is simple to prepare, shortens the smelting time, reduces the oxidation degree of the alloy and obtains the low-melting-point alloy with higher purity.

The foregoing has outlined the basic principles, features, and advantages of the present application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present application, and various changes and modifications may be made therein without departing from the spirit and scope of the application, which is defined by the appended claims. The scope of the application is defined by the appended claims and equivalents thereof.

Claims

1. The preparation method of the low-melting-point tin-based alloy is characterized by comprising the following smelting steps of: preheating a container in a heating furnace at 1000-2000 ℃ for 20-60min, adding doped metal into the container, and adding tin into the container after the doped metal is completely melted to obtain alloy melt; the doped metal comprises copper and silver, wherein the mass fraction of the copper is 2% -6%, the mass fraction of the silver is 2% -6%, the mass fraction of the tin is 88% -96%, in the smelting step, the silver is firstly added into the container, the copper is added after the silver is completely melted, and the tin is added into the container after the copper is completely melted, so that the alloy melt is obtained.

2. The method of claim 1, wherein the furnace temperature is 1000-1200 ℃.

3. The method of manufacturing according to claim 1 or 2, characterized in that the smelting step is followed by a degassing step, an ingot casting step, a cooling step and a polishing step:

and (3) degassing: clamping the container after no slag exists on the surface of the alloy melt, fully stirring the container by using a carbon rod, putting a reducing agent on the container to reduce and degas the alloy melt, and stirring the container again after complete reduction to ensure that the surface of the alloy melt is clear and free of impurities, thus obtaining reduced alloy melt;

ingot casting: pouring the reduced alloy melt into a pre-cleaned ingot mould, and then sealing the ingot mould to avoid oxidation of the alloy in the cooling process;

4. The method of producing according to claim 3, wherein the smelting step is preceded by a preparation step of:

5. A method of preparing as claimed in claim 3, wherein the reducing agent used in the degassing step is rosin.

6. A temperature protection element, characterized in that it is manufactured by the manufacturing method according to any one of the above claims 1 to 5.