Fused Alumina Patents: Top Companies & Filing Trends 2026
- Four assignees hold every record in scope. The ranked leaders account for 100% of the 20 records tracked here, with no long tail beyond them in this dataset.
- Filing activity peaked in 2018 and has since gone flat. Volume ran to 7 filings that year and sat at 1 by the 2022 midpoint, with no recovery visible through the most recent year.
- Grinding-tool claims (B24D) sit under ceramics claims (C04B) in most filings. 85.0% of the 20 records carry a C04B class and 65.0% carry B24D, so most abrasive-grain filings are framed as refractory or ceramic compositions first.
What this landscape covers
This landscape tracks patent filings at the intersection of fused alumina production and abrasive grain manufacturing — electric arc fusion, crystal size control, toughness-and-friability grading, and sol-gel abrasive routes, filtered to records classified under C01F7, C09K3 or B24D3. The scope is narrow by design: 20 published records across a decade of filing activity, concentrated almost entirely among a small set of established abrasives manufacturers.
Because publication lags filing by roughly 18 months, the most recent year in the trend line will read lower than actual filing activity once later applications publish. Readers should treat the last one to two years of any chart here as provisional rather than final.
Filing trend and technology composition
Two views of the same 20-record dataset: how filing volume has moved year over year, and how those filings distribute across IPC subclasses.
A single peak year, then decline
Filings ran to zero in 2017, rose to a peak of 7 in 2018, then fell back toward zero — the 2022 midpoint shows only 1 filing, and the most recent year (partial) shows 0. This is a flat-to-declining trend line, not a growth curve.
Ceramics framing dominates over dedicated abrasive-tool classes
Every record in scope carries a C09K materials class, and 85.0% also carry C04B (ceramics, cement and refractories). B24D (grinding tools and abrasives) appears in 65.0% of records and B24B (grinding and polishing) in 30.0% — abrasive-grain innovation here is claimed more often as a material composition than as a finished grinding tool.
Shares are the percentage of the 20 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Fused Alumina and Abrasive Grain Production with Eureka
This page is one run against one query. Ask Eureka your own question about fused alumina and abrasive grain production and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited prior art in this space
US4988370A — Alumina bonded abrasive for cast iron
This invention concerns the discovery that sol-gel process alumina abrasive grain provides superior performance in bonded abrasives for grinding cast iron. In a preferred form it is disclosed that bonded abrasives of sol-gel process alumina abrasives in combination with other abrasive grains such as those of silicon carbide and fused alumina also provide superior grinding of cast iron.Filed by Minnesota Mining and Manufacturing Company (3M); one of a cluster of related filings on cast-iron grinding abrasives that dominate the citation table.
View full record| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4800685A | Alumina bonded abrasive for cast iron | 304 |
| 2 | US5139539A | Alumina bonded abrasive for cast iron | 20 |
| 3 | US4988370A | Alumina bonded abrasive for cast iron | 11 |
| 4 | US4883501A | Alumina bonded abrasive for cast iron | 11 |
| 5 | EP0171034B2 | Vitrified grinding wheel | 2 |
| 6 | US20210102105A1 | Agglomerate abrasive grain | 1 |
| 7 | US5139536A | Alumina bonded abrasive for cast iron | 1 |
Citation counts favour older filings inside any searched corpus — read them as a signal of influence on later filers, not as a measure of current relevance.
Publication numbers are shown where the record carries one (7 of 7 rows); clicking a row searches Eureka by that number.
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Browse MCP servers →What the data actually shows
Four things worth registering before reading the assignee table below.
No long tail in this dataset
The top 4 ranked assignees combined account for every record in scope. There is no visible fringe of single-filing entrants here — filing in this space has stayed inside a small, established group.
Filing has stalled across the board
Every ranked assignee shows zero filings in the latest tracked year. Combined with a 2018 peak of 7 and a 2022 midpoint of just 1, the pattern reads as declining rather than merely quiet.
US and India lead the receiving offices
The United States receives the largest share of filings, with India second. Europe (EPO), Australia, Canada and Austria each register a small number, suggesting protection strategy is concentrated rather than globally spread.
Ceramics classification outweighs dedicated abrasive-tool classes
Most filings are classified as ceramic or refractory compositions (C04B) alongside the universal C09K materials class, ahead of the dedicated grinding-tool class B24D. That framing choice matters for anyone drafting around this art.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to fused alumina and abrasive grain production, with the prior art for and against each one.
Who holds the ranked claims
Four assignees account for the entire ranked set of 20 records. All four show zero filings in the most recent tracked year, which is consistent with the flat-to-declining trend line above rather than an anomaly of any single company.
One assignee holds half the ranked set
The leading assignee's 10 records represent half of all 20 records in the ranking, making it the single largest holder of claim space in this dataset by a wide margin over the remaining three.
A closed group of incumbents
Beyond the leader, the remaining three ranked assignees are all established abrasives or grinding-tool manufacturers with existing product lines in fused alumina and bonded abrasives, not new entrants.
No active filer in the most recent window
None of the four ranked assignees filed a published record in the latest tracked year. Read against an already-flat trend since 2018, this points to a mature, low-activity corner of the abrasives art rather than a temporarily quiet one.
| Assignee | Recent year | YoY |
|---|---|---|
| Imerys | 0 | — |
| 3M Company | 0 | — |
| CARBORUNDUM UNIVERSAL LIMITED | 0 | — |
| Norton Company (USA) | 0 | — |
Where to take this analysis
This landscape flags where claim density and white space sit today. Turning that into a filing or freedom-to-operate decision means going deeper on the specific claims involved.
Run a freedom-to-operate check on cast-iron abrasive claims
The most-cited records in this set cluster tightly around alumina bonded abrasives for cast-iron grinding. Any new filing touching that use case should be checked against this cluster specifically, not just the broader fused alumina art.
Explore claims in EurekaModel the sol-gel and mixed-grain branches
Sol-gel process alumina abrasive grain, and its combination with fused alumina and silicon carbide grains, appears as a distinct technical route in the representative filing. It is worth mapping separately from pure fused-alumina claims.
Map this branch in EurekaWatch for renewed filing activity
With all four ranked assignees at zero filings in the latest year and a trend that has been flat since 2018, any new filer entering this space would be moving into genuinely quiet claim territory.
Set a monitoring alert in EurekaCommon questions about fused alumina patents
Four assignees account for the entire ranked set of 20 records in this dataset, and together they cover 100.0% of all records in scope. The leading assignee alone holds 10 of those 20 records, roughly half the total, with the remaining three ranked assignees splitting the rest. All four are established abrasives or grinding-tool manufacturers rather than recent entrants, and none has filed a published record in the most recent tracked year.
Not by the evidence in this dataset. Filing activity peaked at 7 records in 2018, fell to just 1 by the 2022 midpoint, and shows 0 filings across every ranked assignee in the most recent tracked year. Because publication lags filing by roughly 18 months, the very latest year is always understated, but the multi-year decline visible before that point is a genuine signal, not an artefact of the lag.
US4988370A, assigned to Minnesota Mining and Manufacturing Company, covers bonded abrasives that use sol-gel process alumina abrasive grain for grinding cast iron, including combinations of that sol-gel grain with other abrasive grains such as silicon carbide and fused alumina. It is one of a small cluster of highly cited cast-iron grinding abrasive patents in this dataset, several of which share the same title and family lineage. Anyone developing a bonded abrasive product for cast-iron grinding that blends sol-gel and fused alumina grains should review this filing and its close relatives directly.
The United States receives the largest share of filings in this dataset with 7, followed by India with 5 and the European Patent Office with 3. Austria, Australia and Canada each register a single filing. This distribution suggests companies in this space protect their core inventions in a small number of jurisdictions rather than filing broadly worldwide.
The IPC composition shows dense coverage of ceramics and refractory framing (C04B, 85.0% of records) and the universal materials class C09K (100.0%), with comparatively thinner coverage of dedicated grinding and polishing claims (B24B, 30.0%). Sub-areas such as sol-gel alumina grain morphology control, crystal size control specific to electric arc fusion, and toughness-and-friability grading protocols appear underrepresented relative to the core cast-iron and vitrified-wheel claims that dominate the most-cited records. These are reasonable starting points for a novelty search before drafting a new application.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.