CN102441675B - Preparation method for high-crystallinity silver powder - Google Patents
Preparation method for high-crystallinity silver powder Download PDFInfo
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- CN102441675B CN102441675B CN201110400908.8A CN201110400908A CN102441675B CN 102441675 B CN102441675 B CN 102441675B CN 201110400908 A CN201110400908 A CN 201110400908A CN 102441675 B CN102441675 B CN 102441675B
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Abstract
The invention relates to a preparation method for high-crystallinity silver powder. The preparation method is characterized by comprising the following steps of: firstly, synthesizing a silver carbonate precursor; uniformly coating the silver carbonate precursor by using a coating agent; and performing low-temperature crystal water removing, high-temperature thermal decomposition, densification sintering and washing on the coated silver carbonate precursor to obtain high-crystallinity silver powder. Due to the adoption of the method disclosed by the invention, high-crystallinity silver powder of which the particle diameter is 0.1-5 mu m and the tap density is 3.0-7.0 g/cm<3> can be finally obtained; the silver powder can be used for preparing silver slurry or silver paste for fine threads and high-accuracy printed galvanic circles; the silver powder has the advantages of high dispersity, high crystallinity, superior degree of sphericity, uniform particle size distribution, easiness for dispersing in silver slurry or silver paste and high filling characteristic, so that high-accuracy fine thread printing can be realized; and meanwhile, an obtained silver thick film has low sintering concentration rate and low bulk resistivity.
Description
Technical field
The present invention relates to technical field of nonferrous metal processing, relate in particular to the coated silver carbonate precursor of a kind of carbonate or bicarbonate, then obtain the preparation method of high-crystallinity ball shape silver powder through decomposition and densification sintering under the de-crystallization water, high temperature under low temperature.
Background technology
Ball shape silver powder is widely used on glass, pottery, silicon and forms thick film circuit owing to having good filling characteristic, adopt after ball shape silver powder is dispersed in to organic carrier and be printed on substrate, form silver thick film circuit by low-temperature setting and high temperature sintering, especially when the silver thick film electrode of formation during in fine rule situation ball shape silver powder should there is good high temperature resistance shrinkage, require ball shape silver powder to there is high crystallization property.Silver powder high crystalline is relevant with silver powder particles crystallite dimension, and microcrystal grain size is larger, and it is less that the crystallite in sintering produces contraction, and institute's thick-film conductor that obtains is better.Therefore, in order to reduce the contraction of silver powder, must improve the size of microcrystal grain in silver powder, crystallite is larger, and the crystallinity of silver powder is better.
The crystallinity of silver powder is relevant with its preparation method, in existing patent, has liquid phase reduction, thermolysis process about the preparation method of high crystalline ball shape silver powder.What wherein relate to liquid phase reduction has patent documentation CN101218051A, patent documentation JP 2000-1706, patent documentation JP 2000-1706, a patent documentation JP 2003-49202 etc., and these patents finally obtain microcrystal grain size and all exist
below, the silver powder crystallite dimension being obtained as the highly crystalline silver powder preparation method who describes in patent documentation CN101218051A is greater than
the crystallite dimension of the silver powder that the highly crystalline silver powder preparation method who describes in patent documentation JP 2000-1706 obtains is greater than
the crystallite dimension scope of the silver powder that the highly crystalline silver powder preparation method who describes in patent documentation JP 2003-49202 obtains is
but above-mentioned patent does not illustrate detection method to the description of crystallite dimension.
The patent that relates to thermolysis process has:
It is the method that atomizing thermolysis process is prepared high-crystallinity ball shape silver powder that open patent 2003-286502 and US5439502 have described a kind of vapor phase method that adopts, this method can obtain the ball shape silver powder that crystallinity is high, but equipment needed thereby complexity, energy consumption are large, gained silver powder particle size distribution is wide, need follow-up multiple fractionation to process the silver powder that just can obtain narrower size distribution, and obtain to such an extent that purity, the compactness of ball shape silver powder can not guarantee, easily obtain hollow ball shape silver powder.Patent JP10183208A has described the method that solid-phase thermal decomposes silver powder, use silver oxide as precursor, after silver oxide is mixed with one of alkali salt, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, under air atmosphere, add thermal decomposition, obtain particle diameter 0.1～5 μ m particulate silver powder.This patent is the effect that silver oxide and coating mechanical mixture is reached to isolation, owing to the method for presoma and coating mechanical mixture can not being guaranteed completely to isolation mutually between presoma, therefore obtains silver powder particles monodispersity, sphericity is poor; And these phenomenons, along with the rising meeting of heat treatment temperature is more obvious, finally reduce tap density and the filling characteristic of silver powder.
Summary of the invention
Object of the present invention is just to overcome the defect of above-mentioned prior art, and a kind of preparation method of the high-crystallinity ball shape silver powder of taking into account dispersiveness, degree of crystallinity, tap density is provided, and the method flow process controllability is good, and is easy to realize large-scale industrial production.
The technical scheme taked is for achieving the above object:
A kind of preparation method of high-crystallinity ball shape silver powder, it is characterized in that: first with wet-precipitated carbonate synthesis silver precursor, again with evenly coated silver carbonate precursor of covering, through the low temperature de-crystallization water, high temperature thermal decomposition and densification sintering, after washing, obtain high-crystallinity ball shape silver powder through the coated silver carbonate precursor of processing;
Above-mentioned wet-precipitated carbonate synthesis silver precursor refers to liquor argenti nitratis ophthalmicus is mixed with carbonate solution, the silver carbonate precursor precipitation obtaining by Separation of Solid and Liquid;
Above-mentioned with covering evenly coated silver carbonate precursor refer to the coated silver carbonate of method that adopts heterogeneous forming core, be take silver carbonate precursor as nucleus specifically, form clad or use chemical precipitation modification method to form clad on silver carbonate surface at silver carbonate surface crystallization by physical crystal method;
Described covering is carbonate or bicarbonate;
The mol ratio of above-mentioned silver carbonate precursor and described covering is 1:0.2～5;
Described covering is potash, lithium carbonate, magnesium carbonate, calcium carbonate, saleratus or sodium acid carbonate;
The de-crystallization water of described low temperature refers to that be coated product processes 1～100 hour to slough the crystallization water that covering is with at 50 ℃～300 ℃;
Described high temperature thermal decomposition and densification sintering refer at 300 ℃～1000 ℃ roasting 1～100 hour;
The particle size distribution range of described high-crystallinity ball shape silver powder is 0.1～5 μ m, and tap density is at 3.0～7.0g/cm3;
The silver powder crystallite dimension that uses X-ray diffraction half-peak breadth to calculate is greater than
The present invention has following technical characterstic:
1. the present invention adopts that wet-precipitated is synthetic to combine and prepare silver powder with pyrogenic process, and the silver powder obtaining has the advantages such as monodispersity, any surface finish, crystallinity and sphericity be good.
2. the present invention adopts wet-precipitated to obtain presoma, and presoma is coated, and this processing mode can make presoma obtain the heat treatment of higher temperature and longer time, thereby reduces the possibility of hollowization of silver powder and improved its degree of crystallinity.
3. the present invention adopts silver carbonate as presoma, and adopt the method for heterogeneous forming core to be coated, this processing mode can realize evenly coated, between particle, isolate effective, thereby the not impact of heat-treated temperature and time still has good single dispersing characteristic, higher tap density after long-time high-temperature process.
Finally can obtain particle size distribution range at 0.1～5 μ m by method of the present invention, tap density is at the high-crystallinity ball shape silver powder of 3.0～7.0g/cm3, this silver powder can be for making fine rule, high accuracy printing conductive loop silver slurry or silver paste, due to its good dispersion, degree of crystallinity is high, sphericity is good, broad particle distribution, in silver slurry or silver paste, be easy to disperse and have good filling characteristic, can obtain the fine rule printing of pinpoint accuracy, the silver thick film sintering shrinkage simultaneously obtaining is little, and body resistivity is low.
Method of the present invention, aspect cost, physical and chemical performance, there is clear superiority compared with existing high-crystallinity method for preparing spherical silver powder, can meet the application requirements of the ball shape silver powder of the needs low frit shrinkage factors such as current PDP, LTCC, silicon solar cell front side silver paste, chip original paper.
Accompanying drawing explanation
Fig. 1 is SEM × 10k shape appearance figure of silver carbonate described in the inventive method;
Fig. 2 is SEM × 10k shape appearance figure of particle size range 0.2～1.0 μ m silver powder of the inventive method gained;
Fig. 3 is SEM × 10k shape appearance figure of particle size range 1.0～3.0 μ m silver powder of the inventive method gained;
Fig. 4 is the X-ray diffractogram of the high-crystallinity ball shape silver powder of the inventive method gained.
The specific embodiment
The present invention prepares the implementation step of the method for high-crystallinity ball shape silver powder:
The first step: prepare silver carbonate precursor, specifically liquor argenti nitratis ophthalmicus is mixed with carbonate solution, the precursor precipitation obtaining by Separation of Solid and Liquid.Obtain varigrained silver carbonate precursor according to the change of deposition condition;
Second step: with physics or chemistry heterogeneous forming core method for crystallising carbonate or bicarbonate are evenly coated on silver carbonate precursor;
The 3rd step: low temperature (50～300 ℃) treatment step two gained materials, slowly slough the crystallization water that coating is with;
The 4th step: high-temperature process second step gained material, obtains high-crystallinity ball shape silver powder by this material through washing or pickling, after dry after cooling.
Embodiment 1:
170g is analyzed to pure silver nitrate and adds in 1000ml pure water and dissolve, then 58.3g sodium carbonate is added in 500ml pure water and dissolved, liquor argenti nitratis ophthalmicus is added fast in sodium carbonate liquor and stirs 10min, after reaction 20min, leave standstill clarification after suction filtration obtain silver carbonate filter cake.
138g is analyzed to pure potash and add in 130ml water, be stirred to molten clear.Silver carbonate filter cake is joined in solution of potassium carbonate and strong stirring mixing, thereby the water that uses physical method to slough in solution of potassium carbonate make potash take silver carbonate as core, and crystallization in its surface, will be coated product suction filtration, 60 ℃ of oven dry 24h of gained filter cake.To dry afterproduct roasting 1.5h at 600 ℃.Add abundant agitator treating in 1000ml pure water to obtain silver powder product of roasting, by silver powder vacuum drying 8h at 55 ℃.
Obtain 96g silver powder through weighing, under SEM × 10k observes, silver powder is monodisperse particles, good sphericity, and any surface finish, average grain diameter 0.8 μ m records tap density 4.4g/cm simultaneously
3, specific surface 0.7m
2/ g.
Embodiment 2:
85g is analyzed to pure silver nitrate and add in 2000ml pure water and dissolve, then 30g sodium carbonate is added in 1000ml pure water and dissolved, limit is stirred sodium carbonate liquor limit and is slowly dripped wherein liquor argenti nitratis ophthalmicus, after reaction 30min, leave standstill clarification after suction filtration obtain silver carbonate filter cake.
By 65g sodium acid carbonate add in 620ml water, stir molten clear, again silver carbonate filter cake is joined in sodium bicarbonate solution and strong stirring mixing, use physical method that sodium bicarbonate solution is slowly dewatered and makes evenly crystallization on silver carbonate of sodium acid carbonate, suction filtration obtain coated product filter cake at 60 ℃ of oven dry 24h.To dry afterproduct roasting 2h at 660 ℃.Add abundant agitator treating in 1000ml pure water to obtain silver powder product of roasting, by silver powder vacuum drying 8h at 55 ℃.
Obtain 48g silver powder through weighing, under SEM × 10k observes, silver powder is monodisperse particles, good sphericity, and any surface finish, average grain diameter 2.0 μ m record tap density 5.7g/cm simultaneously
3, specific surface 0.29m
2/ g.
Embodiment 3:
340g is analyzed to pure silver nitrate and adds in 1500ml pure water and dissolve, then 120g sodium carbonate is added in 1000ml pure water and dissolved, liquor argenti nitratis ophthalmicus is added fast in sodium carbonate liquor and stirs 10min, after reaction 20min, leave standstill clarification after suction filtration obtain silver carbonate filter cake.
414g is analyzed to pure potash and add in 350ml water, be stirred to molten clear.Silver carbonate filter cake is joined in solution of potassium carbonate and strong stirring mixing, thereby the water that uses physical method to slough in solution of potassium carbonate make potash take silver carbonate as core, and crystallization in its surface, will be coated product suction filtration, 120 ℃ of oven dry 24h of gained filter cake.To dry afterproduct roasting 1.5h at 750 ℃.Add abundant agitator treating in 1000ml pure water to obtain silver powder product of roasting, by silver powder vacuum drying 8h at 55 ℃.
Obtain 202g silver powder through weighing, under SEM × 10k observes, silver powder is monodisperse particles, good sphericity, and any surface finish, average grain diameter 1.3 μ m record tap density 5.2g/cm simultaneously
3, specific surface 0.57m
2/ g.
Embodiment 4:
136g is analyzed to pure silver nitrate and add in 1500ml pure water and dissolve, then 47g sodium carbonate is added in 800ml pure water and dissolved, limit is stirred sodium carbonate liquor limit and is added wherein liquor argenti nitratis ophthalmicus, after reaction 30min, leave standstill clarification after suction filtration obtain silver carbonate filter cake.
Get 85g and analyze pure sodium carbonate and add in 2000ml pure water molten clearly, then get 204g and analyze pure magnesium nitrate and add in 1000ml pure water molten clear.After first silver carbonate filter cake being added in magnesium nitrate solution, add while stirring again sodium carbonate liquor; make magnesium carbonate take silver carbonate as nucleus and precipitate and form clad by chemical reaction on its surface; add rear reaction 1h suction filtration, after suction filtration, filter cake is dried 10h at 100 ℃; To dry afterproduct roasting 2h at 850 ℃.Get 80g sulfuric acid dissolution in 1000ml pure water, product of roasting is added in 1000ml sulfuric acid solution fully to stir wash away magnesia and obtain silver powder, by silver powder vacuum drying 8h at 55 ℃.
Obtain 78g silver powder through weighing, under SEM × 10k observes, silver powder is monodisperse particles, good sphericity, and any surface finish, average grain diameter 1.5 μ m record tap density 5.0g/cm simultaneously
3, specific surface 0.4m
2/ g.
Reference examples:
It is silver nitrate that weighing 340g analyzes pure, and with the dissolving of 4L pure water, the ammoniacal liquor that weighing 280g mass concentration is 25% joins stirring in liquor argenti nitratis ophthalmicus and forms silver ammino solution, and heats this silver ammino solution to 70 ℃; The hydrazine hydrate that weighing 40g mass concentration is 80% joins in 1L pure water and dissolves; Weigh 1.5g stearic acid and 5g triethanolamine and mix with 50ml pure water, add this mixed solution of thermal agitation until clarification completely.
The hydrazine hydrate solution configuring is added in silver ammino solution and rapid stirring fast; When adding stearic acid and triethanolamine mixed aqueous solution after bubble collapse in course of reaction and continuing to stir 20min.Washing suction filtration is also dry, obtains 210g silver powder product through weighing.It is monodisperse spherical particle that SEM observes silver powder particles, specific surface value 0.88m
2/ g, tap density 3.5g/cm
3.
Following table is that highly crystalline silver powder and the wet chemistry reduction silver powder reference examples X-ray diffraction of the inventive method gained calculates crystallite dimension comparison sheet.
Claims (2)
1. the preparation method of a high-crystallinity ball shape silver powder, it is characterized in that: first liquor argenti nitratis ophthalmicus is mixed with carbonate solution, the silver carbonate precursor obtaining by Separation of Solid and Liquid, again take silver carbonate precursor as nucleus, be that covering is evenly coated on silver carbonate precursor by carbonate or bicarbonate, then by the coated silver carbonate precursor suction filtration of processing, at 50 ℃～300 ℃, process and within 1～100 hour, slough the crystallization water that covering is with, roasting 1～100 hour at 850 ℃, after washing, obtaining particle size distribution range is 0.1～5 μ m, tap density is at 3.0～7.0g/cm3, the high-crystallinity ball shape silver powder that crystallite dimension is greater than 900,
The mol ratio of described silver carbonate precursor and described covering is 1:0.2～5.
2. according to the preparation method of high-crystallinity ball shape silver powder claimed in claim 1, it is characterized in that described covering is potash, lithium carbonate, magnesium carbonate, calcium carbonate, saleratus or sodium acid carbonate.
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| CN102699344A (en) * | 2012-05-18 | 2012-10-03 | 西北稀有金属材料研究院 | Method for preparing micron-scale high-crystallinity spherical silver powder |
| CN102699338B (en) * | 2012-05-18 | 2014-06-04 | 国家钽铌特种金属材料工程技术研究中心 | Method for preparing spherical nickel powder |
| CN103737013A (en) * | 2013-12-20 | 2014-04-23 | 宁夏东方钽业股份有限公司 | Method for preparing nanometer spherical copper powder |
| CN110303148B (en) * | 2019-06-14 | 2021-07-20 | 湖南诺尔得材料科技有限公司 | Preparation method of nearly spherical silver powder |
| CN110449572B (en) * | 2019-08-08 | 2021-07-20 | 湖南诺尔得材料科技有限公司 | Preparation method of functional silver powder for electronic paste |
| CN111834031A (en) * | 2020-06-29 | 2020-10-27 | 河南金渠银通金属材料有限公司 | Silver powder for ceramic filter conductive silver paste and preparation method thereof |
| CN113385688B (en) * | 2021-05-27 | 2023-03-24 | 湖南中伟新银材料科技有限公司 | Preparation method and application of silver powder |
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Non-Patent Citations (2)
| Title |
|---|
| THERMAL DECOMPOSITION OF SILVER CARBONATE:EFFECT OF ADDITION OF ALKALINE EARTH AND ALKALI METAL COMPOUNDS;V.R.CHOUDHARY etal;《Materials Chemistry and Physics》;19861231;第14卷(第1期);第9-23页 * |
| V.R.CHOUDHARY etal.THERMAL DECOMPOSITION OF SILVER CARBONATE:EFFECT OF ADDITION OF ALKALINE EARTH AND ALKALI METAL COMPOUNDS.《Materials Chemistry and Physics》.1986,第14卷(第1期),第9-23页. |
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