CN110256065A - A kind of dense oxide titanium nano ceramics and its preparation method and application - Google Patents
A kind of dense oxide titanium nano ceramics and its preparation method and application Download PDFInfo
- Publication number
- CN110256065A CN110256065A CN201910654874.1A CN201910654874A CN110256065A CN 110256065 A CN110256065 A CN 110256065A CN 201910654874 A CN201910654874 A CN 201910654874A CN 110256065 A CN110256065 A CN 110256065A
- Authority
- CN
- China
- Prior art keywords
- nano ceramics
- dense oxide
- preparation
- oxide titanium
- titanium nano
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
- C04B35/645—Pressure sintering
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
- C04B2235/54—Particle size related information
- C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
- C04B2235/5454—Particle size related information expressed by the size of the particles or aggregates thereof nanometer sized, i.e. below 100 nm
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
- C04B2235/602—Making the green bodies or pre-forms by moulding
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
- C04B2235/6567—Treatment time
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
- C04B2235/66—Specific sintering techniques, e.g. centrifugal sintering
- C04B2235/661—Multi-step sintering
- C04B2235/662—Annealing after sintering
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
- C04B2235/74—Physical characteristics
- C04B2235/77—Density
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
- C04B2235/74—Physical characteristics
- C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
- C04B2235/781—Nanograined materials, i.e. having grain sizes below 100 nm
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
The invention discloses a kind of dense oxide titanium nano ceramics and its preparation method and application, belong to nano ceramics technical field.Use nano titania for raw material, it is sintered 10min under die material high temperature high pressure, abnormal grain growth is effectively inhibited, removes pressure after sintering, it is cooled to 600 DEG C of heat preservation 4h, product can be promoted further to densify, product crystal grain is tiny, is in Nano grade, product is shunk close to zero simultaneously, product cost can be greatly lowered in short preparation period, have higher economic benefit.The dense oxide titanium nano ceramics of preparation, relative density, crystallite dimension, shrinking percentage performance indicator are excellent.It can be used as stealth material, ultraviolet shielded materials'use.
Description
Technical field
The invention belongs to nano ceramics technical fields, and in particular to a kind of dense oxide titanium nano ceramics and preparation method thereof
And application.
Background technique
Dense oxide titanium nano ceramics with its distinctive performance stealth material, in terms of have and answer extensively
With.Nanometer ceramic of compact preparation core process problem includes two aspects, first is that guarantee that sintered article inside configuration is nanocrystalline, this
Aspect has studied rather maturation at present, i.e., using being rapidly heated between high temperature, short time, sintering and low temperature long-time heat preservation can be real
It is existing;Second is densification, and it is that product consistency is difficult to improve that existing main problem is sintered after powder compacting.Ceramic densifying
Technique apparently develops relatively slowly at present, or mainly includes hot pressed sintering, liquid-phase sintering using conventional densification process is segmented
Three classes are sintered with self- propagating.Sintered body consistency can be improved in hot pressed sintering to a certain extent, but high temperature is due to using stone
Black mould strength is low to cause high temperature pressure to be difficult to effectively improve, and high temperature pressure is well below conventional ceramic low temperature moulding pressure;Liquid
Phase sintering can also improve consistency to a certain extent, but the introducing of high temperature bond phase affects main body to a certain extent
Material property plays, and mutual " conflict " also leads to green body there are certain amounts between Polyhedral Particles during low temperature moulding
Stomata, secondly the addition of high-temperature fusant phase causes product deformation larger, is unfavorable for later period application and processing, last titanium oxide high temperature
There are small density Anatases to change to big density Rutile Type, also causes sample structure loose to a certain extent, these are right
Consistency raising is all unfavorable;For self- propagating sintering is mainly for some special ceramic materials.Thus develop it is a kind of efficiently,
Simply, the technique that can effectively improve nano ceramics consistency is current urgent problem to be solved.
Summary of the invention
To solve the above-mentioned problems, the purpose of the present invention is to provide a kind of dense oxide titanium nano ceramics and its preparation sides
Method and application, product crystal grain is tiny, is in Nano grade, while product is shunk close to zero, short preparation period can significantly drop
Low product cost has higher economic benefit, and the present invention is to be achieved through the following technical solutions:
The invention discloses a kind of methods of dense oxide titanium nano ceramics, are divided into following steps:
1) nano titania is subjected to wet ball grinding, it is dry, it is granulated after sieving;
2) step 1) is granulated obtained particle and is put into die material, 700~900 DEG C are warming up at 150~450Mpa
Pressure is removed after heat preservation 10min, 600 DEG C of heat preservation 4h is cooled to, cools to room temperature with the furnace, obtain dense oxide titanium nano ceramics.
Preferably, the average particle size of nano titania is 7nm.
Preferably, the detailed process of wet ball grinding are as follows: alcohol is added into nano titania, using planetary type ball-milling
Machine carries out ball milling.
Preferably, the time of wet ball grinding is 30min.
Preferably, dry using rotary dry evaporimeter.
Preferably, sieving was the sieve of 120 mesh.
Preferably, the material of die material is fused alumina zirconia ceramic of compact.
The invention also discloses using the above method preparation dense oxide titanium nano ceramics, relative density be 3.01%~
4.16%, crystallite dimension is 30~95nm, and shrinking percentage is 0.4511%~0.7312%.
The invention also discloses the application of the dense oxide titanium nano ceramics as stealth material, ultraviolet shielded material.
Compared with prior art, the invention has the following beneficial technical effects:
The method of dense oxide titanium nano ceramics of the invention, sintering time is under die material high temperature high pressure
10min effectively inhibits abnormal grain growth, removes pressure after sintering, is cooled to 600 DEG C of heat preservation 4h, can promote product into
The densification of one step, product crystal grain is tiny, is in Nano grade, while product is shunk close to zero, short preparation period can be significantly
Product cost is reduced, there is higher economic benefit.
Further, wet ball grinding is carried out using planetary ball mill, in order to the reunion of powder internal particle is reduced,
Convenient for later period moulding process.
Further, it is dried using Rotary Evaporators it is possible to prevente effectively from different in general static drying process
Grain causes powder to be layered and mix non-uniform phenomenon because density variation causes sinking speed.
Further, die material material is fused alumina zirconia ceramic of compact, has good heat-resistant pressure-resistant performance, improves burning
Temperature and pressure when knot.
The dense oxide titanium nano ceramics prepared using the above method of the invention, relative density, crystallite dimension, shrinking percentage
Performance indicator is excellent.
When dense oxide titanium nano ceramics of the invention is as stealth material, ultraviolet shielded materials'use, have good
Effect.
Specific embodiment
Below with reference to specific embodiment, the present invention is described in further detail, it is described be explanation of the invention and
It is not to limit.
A kind of preparation method of dense oxide titanium nano ceramics disclosed by the invention:
Embodiment 1
1) alcohol is added into the nano titania that average particle size is 7nm, wet process is carried out using planetary ball mill
Ball milling 30min is dried using rotary dry evaporimeter, crosses 120 meshes after dry and be granulated;
2) obtained particle will be granulated and is put into fused alumina zirconia ceramic of compact die material, keep briquetting pressure 150MPa, heating
600 DEG C of heat preservation 4h are cooled to after to 700 degrees Celsius of heat preservation 10min, cool to room temperature with the furnace, obtain dense oxide titanium nanometer pottery
Porcelain.Relative density, crystallite dimension, the shrinking percentage measured is shown in Table 1.
In the situation that remaining condition is constant, the embodiment 2~9 that change sintering temperature and pressure are carried out as shown in table 1, is made
The relative density of the dense oxide titanium nano ceramics obtained, crystallite dimension, contraction rate score are as shown in table 1.
Table 1
As can be seen from Table 1, the dense oxide titanium nano ceramics cause with higher that case study on implementation 3,5,6,8 and 9 is prepared
Density, nanocrystal size shrink almost very little between 30-95nm.
Claims (9)
1. a kind of preparation method of dense oxide titanium nano ceramics, which is characterized in that be divided into following steps:
1) nano titania is subjected to wet ball grinding, it is dry, it is granulated after sieving;
2) step 1) is granulated obtained particle and is put into die material, 700~900 DEG C of heat preservations are warming up at 150~450Mpa
Pressure is removed after 10min, is cooled to 600 DEG C of heat preservation 4h, is cooled to room temperature with the furnace, obtain dense oxide titanium nano ceramics.
2. the preparation method of dense oxide titanium nano ceramics according to claim 1, which is characterized in that nano oxidized titanium valve
The average particle size of body is 7nm.
3. the preparation method of dense oxide titanium nano ceramics according to claim 1, which is characterized in that the tool of wet ball grinding
Body process are as follows: alcohol is added into nano titania, ball milling is carried out using planetary ball mill.
4. the preparation method of dense oxide titanium nano ceramics according to claim 1, which is characterized in that wet ball grinding when
Between be 30min.
5. the preparation method of dense oxide titanium nano ceramics according to claim 1, which is characterized in that dry using rotation
Formula dries evaporimeter.
6. the preparation method of dense oxide titanium nano ceramics according to claim 1, which is characterized in that sieving was 120
Purpose sieve.
7. the preparation method of dense oxide titanium nano ceramics according to claim 1, which is characterized in that the material of die material
Matter is fused alumina zirconia ceramic of compact.
8. fine and close oxygen prepared by the preparation method using dense oxide titanium nano ceramics described in claim 1~7 any one
Change titanium nano ceramics, relative density be 3.01%~4.16%, crystallite dimension be 30~95nm, shrinking percentage be 0.4511%~
0.7312%.
9. application of the dense oxide titanium nano ceramics according to any one of claims 8 as stealth material, ultraviolet shielded material.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201910654874.1A CN110256065A (en) | 2019-07-19 | 2019-07-19 | A kind of dense oxide titanium nano ceramics and its preparation method and application |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201910654874.1A CN110256065A (en) | 2019-07-19 | 2019-07-19 | A kind of dense oxide titanium nano ceramics and its preparation method and application |
Publications (1)
Publication Number | Publication Date |
---|---|
CN110256065A true CN110256065A (en) | 2019-09-20 |
Family
ID=67927183
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN201910654874.1A Pending CN110256065A (en) | 2019-07-19 | 2019-07-19 | A kind of dense oxide titanium nano ceramics and its preparation method and application |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN110256065A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112174644A (en) * | 2020-09-07 | 2021-01-05 | 中国科学院上海光学精密机械研究所 | Method for pressureless rapid sintering of compact nanocrystalline ceramic |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004175623A (en) * | 2002-11-27 | 2004-06-24 | Sumitomo Coal Mining Co Ltd | Nano-structured metal oxide sintered compact having preferred orientation and method of manufacturing the same |
CN102745977A (en) * | 2012-07-25 | 2012-10-24 | 武汉理工大学 | Method for quickly preparing high-density magnesium oxide nanometer ceramics |
CN105645951A (en) * | 2016-01-06 | 2016-06-08 | 昆明理工大学 | Method for promoting phase change of titanium dioxide and inhibiting grain growth |
CN106116545A (en) * | 2016-06-25 | 2016-11-16 | 丁玉琴 | A kind of preparation method with amorphous/nanocrystalline structural ceramic material |
CN108947493A (en) * | 2018-08-09 | 2018-12-07 | 苏州市泽镁新材料科技有限公司 | A kind of preparation method of the nano oxidized magnesium-based ceramics of high-compactness |
-
2019
- 2019-07-19 CN CN201910654874.1A patent/CN110256065A/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004175623A (en) * | 2002-11-27 | 2004-06-24 | Sumitomo Coal Mining Co Ltd | Nano-structured metal oxide sintered compact having preferred orientation and method of manufacturing the same |
CN102745977A (en) * | 2012-07-25 | 2012-10-24 | 武汉理工大学 | Method for quickly preparing high-density magnesium oxide nanometer ceramics |
CN105645951A (en) * | 2016-01-06 | 2016-06-08 | 昆明理工大学 | Method for promoting phase change of titanium dioxide and inhibiting grain growth |
CN106116545A (en) * | 2016-06-25 | 2016-11-16 | 丁玉琴 | A kind of preparation method with amorphous/nanocrystalline structural ceramic material |
CN108947493A (en) * | 2018-08-09 | 2018-12-07 | 苏州市泽镁新材料科技有限公司 | A kind of preparation method of the nano oxidized magnesium-based ceramics of high-compactness |
Non-Patent Citations (2)
Title |
---|
冶银平等: "氧化钛纳米陶瓷的制备及其结构与力学性能", 《中南大学学报》 * |
高廉等: "纳米氧化钛陶瓷的烧结", 《无机材料学报》 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112174644A (en) * | 2020-09-07 | 2021-01-05 | 中国科学院上海光学精密机械研究所 | Method for pressureless rapid sintering of compact nanocrystalline ceramic |
CN112174644B (en) * | 2020-09-07 | 2022-05-31 | 中国科学院上海光学精密机械研究所 | Method for rapidly sintering compact nanocrystalline ceramic under no pressure |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP2604592B2 (en) | Molding method of metal, ceramic powder, etc. and composition therefor | |
JP5647359B2 (en) | Method for preparing α-alumina abrasive | |
Tallon et al. | Effect of particle size on the shaping of ceramics by slip casting | |
CN110128115A (en) | A kind of method that flash burning prepares oxide eutectic ceramics | |
CN107721424B (en) | Method for preparing YAG transparent ceramic by gel casting | |
CN107903043A (en) | A kind of method of aluminium oxide ceramics tape casting | |
CN110128129A (en) | A kind of preparation method of low-loss ferrogarnet material | |
CN108907211A (en) | A method of preparing large scale molybdenum plate blank | |
Chen et al. | Effect of ball-milling granulation with PVB adhesive on the sinterability of co-precipitated Yb: YAG nanopowders | |
WO2015096685A1 (en) | Method for manufacturing metal member having geometric structure such as thin wall or thin groove | |
CN112851342B (en) | Zirconia ceramic material and preparation method and application thereof | |
CN105669181A (en) | Preparation method of compact small-grain YIG ceramic | |
Qian et al. | Effect of nano-TiO2 on properties of 3 mol% yttria-stabilized zirconia ceramic via layered extrusion forming | |
CN114105639A (en) | Infrared transparent ceramic material and preparation method thereof | |
CN110256065A (en) | A kind of dense oxide titanium nano ceramics and its preparation method and application | |
CN112299861A (en) | AlON transparent ceramic pseudo-sintering agent and application thereof, and preparation method of transparent ceramic | |
CN102924087A (en) | Method for preparing cubic born nitride-silicon carbide composite ceramic material and product thereof | |
CN106587940A (en) | High-purity compact magnesium oxide target material and preparation method thereof | |
CN108465817B (en) | Preparation method of high-density pure tungsten product with uniform structure | |
CN108276001A (en) | A kind of super abrasive Talide discharge plasma sintering method | |
Lin et al. | Rheology, packing and sintering behavior in dense suspension of multimodal spherical silica | |
CN107500756A (en) | A kind of high-k low-loss SrTiO3Based dielectric material and preparation method thereof | |
CN103693946B (en) | High-thermal conductivity TiO2-containing microwave attenuating ceramic and preparation method thereof | |
CN111056849A (en) | High-dispersion antiferroelectric submicron ceramic powder and preparation method thereof | |
CN109293365A (en) | A kind of orienting stephanoporate silicon carbide ceramics and its preparation method and application |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
RJ01 | Rejection of invention patent application after publication | ||
RJ01 | Rejection of invention patent application after publication |
Application publication date: 20190920 |