Vacuum Heat Treatment Patents: Who Leads, Where the Gaps Are 2026
- Filing has plateaued, not grown. Annual filings peaked at 7 in 2022 after starting at 5 in 2017, with no sustained upward trend since.
- The field is moderately concentrated. The top 5 assignees hold 37.1% of all 89 records in scope; the top 10 hold 49.4% — leaving roughly half spread across a long tail.
- China dominates the filing venue. 58 of the tracked records were filed via China's receiving office, more than four times the next-largest venue, the United States at 14.
What this landscape covers
Vacuum and controlled-atmosphere heat treatment covers processes that harden, carburize or otherwise transform metal surfaces without an open-air furnace atmosphere — low-pressure carburizing, gas quenching, and the furnace hardware that controls distortion and cycle uniformity. This dataset tracks 89 published records filed between 2015 and mid-2026 that combine those process terms with IPC classes for heat treatment of metals, surface coating, and furnace design. Publication lags filing by roughly 18 months, so the 2025-2026 figures in any trend understate real activity.
The scope spans equipment patents — multi-chamber furnaces, gas-tight chamber divisions, heating systems — as well as process and material claims tied to specific carburizing gas chemistries and steel grades formulated for low-distortion vacuum carburizing.
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Filing trend and technology composition
Two views of the same 89 records: how filing activity has moved year over year, and which IPC subclasses carry the claims.
A flat filing curve since 2017
Annual filings ran from 5 in 2017 to a peak of 7 in 2022, then eased back toward 1 in 2026 (a partial year). The midpoint sitting at the peak year signals a field that grew modestly through the late 2010s and has since leveled off rather than accelerated — read the 2025-2026 dip with the publication-lag caveat in mind rather than as a real collapse.
Heat treatment and coating dominate; furnace hardware is secondary
C21D (heat treatment of metals) appears on 88.8% of the 89 records and C23C (coating and surface deposition) on 48.3%, confirming this is primarily a process and materials field. Furnace and kiln hardware under F27B sits at 18.0%, with furnace accessories (F27D), alloys (C22C), non-ferrous treatment (C22F), corrosion (C23F) and general metalworking (B23P) all in single digits — these lower-share classes are where equipment-side claims are thinner.
Shares are the percentage of the 89 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Vacuum and Controlled Atmosphere Heat Treatment with Eureka
This page is one run against one query. Ask Eureka your own question about vacuum and controlled atmosphere heat treatment and every answer comes back with the patent numbers behind it.
Try EurekaThe documents anchoring this space
Multi-chamber furnace for vacuum carburizing and quenching
A multi-chamber furnace for vacuum carburizing and quenching of gears, shafts, rings and similar components uses at least two process chambers connected in parallel with a continuous feeding mechanism. The chambers — heating, carburizing and diffusion — are arranged vertically inside a shared vacuum space with gas-tight division, each fitted with thermally insulated heating chambers, a graphite heating system, and a stepping feed mechanism for continuous workpiece throughput.Filed by SECO/WARWICK S.A., 2016-08-04.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20030020214A1 | Vacuum carburizing with unsaturated aromatic hydrocarbons | 47 |
| 2 | US20030089426A1 | Vacuum carburizing with napthene hydrocarbons | 31 |
| 3 | US4160680A | Vacuum carburizing | 28 |
| 4 | CN2887886Y | 真空热处理炉 | 25 |
| 5 | JP2008195997A | Steel for low strain vacuum carburizing gas quenching, and low strain carburized component produced therefrom | 20 |
| 6 | US6991687B2 | Vacuum carburizing with napthene hydrocarbons | 19 |
| 7 | US7033446B2 | Vacuum carburizing with unsaturated aromatic hydrocarbons | 18 |
| 8 | US20160223259A1 | Multi-chamber furnace for vacuum carburizing and quenching of gears, shafts, rings and similar workpieces | 14 |
| 9 | US7267793B2 | Furnace for vacuum carburizing with unsaturated aromatic hydrocarbons | 14 |
| 10 | CN102925644A | 一种真空热处理与深冷处理一体机 | 13 |
Citation counts favour older filings that have had more time to accumulate references — treat them as a measure of influence on subsequent filings, not of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Three read-outs from the filing pattern, citation clustering and venue split that matter more than the raw counts.
Moderate concentration, not lockout
The top 5 assignees hold 37.1% of all 89 records and the top 10 hold 49.4% — meaningful clustering, but with just over half the field spread across 47 additional ranked assignees. That is a structure a new entrant can still find room in, provided the claim sits away from the densest chamber and steel-grade claims.
Filing is heavily China-centric
China accounts for 58 of the 89 records, well ahead of the United States (14), Europe and South Korea (4 each), and Canada and India (2 each). Freedom-to-operate work that stops at US and EPO searches will miss the majority of the documented activity in this field.
Older US carburizing chemistry patents still anchor the field
The most-cited records are gas-chemistry patents from the early 2000s and a 1970s foundational vacuum carburizing patent, each cited well ahead of anything more recent. New filings on carburizing gas composition are still being read against this older art.
Leaders have gone quiet in the latest tracked year
Several of the most active historical filers, including one with a -100% year-on-year change, show zero filings in the latest year. Given the roughly 18-month publication lag, this is as likely to reflect filings still in the pipeline as a genuine pullback.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to vacuum and controlled atmosphere heat treatment, with the prior art for and against each one.
Who is filing, and where the gate sits
The ranking covers 57 assignees across the 89 records in scope — a mix of established furnace makers, Chinese research institutes and universities, and a long tail of single-filing entrants.
A single furnace maker leads the ranking
The top-ranked assignee holds 9 of the 89 records, ahead of a fifth-place assignee at 3 and a tenth-place assignee at 2 — a steep drop-off that indicates the leader's position rests on a genuinely larger portfolio, not a marginal edge.
Chinese research institutes are structurally present
Several of the ranked assignees are Chinese universities and state-affiliated research institutes rather than manufacturers, reflecting government-backed R&D into vacuum furnace design and carburizing process control alongside commercial furnace builders.
Co-filing is rare and mostly parent-subsidiary
Only 3 co-assignee pairs appear across the dataset, and the strongest of them links a Chinese parent research institute with its own vacuum technology subsidiary — evidence of internal group filing rather than cross-company joint development.
| Assignee | Recent year | YoY |
|---|---|---|
| SECO/WARWICK S.A. | 0 | — |
| Beijing Research Institute of Mechanical & Electrical Technology, China Academy of Machinery Science and Technology | 0 | — |
| Surface Combustion, Inc. | 0 | — |
| Shenyang Vacuum Technology Institute Co., Ltd. | 0 | -100% |
| Shenyang Dongbo Thermal Technology Co., Ltd. | 0 | — |
| Taiyuan University of Science and Technology | 0 | — |
| Central Iron and Steel Research Institute Co., Ltd. | 0 | — |
| Suzhou Wantai Vacuum Furnace Research Institute Co., Ltd. | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, portfolio strategy, or identifying a filing gap.
Map claims against the leader's granted set
With the top assignee holding 9 of 89 records, a claim-by-claim comparison against its granted family is the fastest way to see whether a planned furnace or process claim sits clear.
Run a claim comparison in Patsnap EurekaExtend the search past China and the US
Europe, South Korea, Canada and India together account for a small but non-trivial share of filings; a venue-by-venue check avoids missing regional blocking patents.
Explore global coverage in Patsnap EurekaWatch the low-share IPC classes
F27D, C22F, C23F and B23P each sit under 10% of records — worth monitoring for early filings before density builds.
Set up class monitoring in Patsnap EurekaCommon questions on this landscape
This dataset tracks 89 published records filed between 2015 and mid-2026 that match vacuum heat treatment, controlled-atmosphere furnace and vacuum carburizing terms combined with the relevant heat-treatment, coating and furnace IPC classes. The true figure is somewhat higher because publication typically lags filing by around 18 months, so 2025 and 2026 filings are undercounted. Treat 89 as the searchable, published baseline rather than a final total.
The ranking covers 57 assignees across the 89 records, led by a single company with 9 records, well ahead of the fifth-ranked assignee at 3 and the tenth-ranked at 2. The field also includes several Chinese universities and state research institutes alongside commercial furnace manufacturers. No single filer controls the space outright — the top 5 combined hold 37.1% of all records, leaving the majority spread across a long tail of smaller filers.
Filing activity rose modestly from 5 records in 2017 to a peak of 7 in 2022, then declined toward 1 in 2026. Because 2026 is a partial year and publication lags filing by roughly 18 months, the recent drop should be read cautiously rather than as confirmed decline. On the data available, the honest read is that filing has plateaued since its 2022 peak rather than continuing to grow.
China's receiving office accounts for 58 of the 89 records in scope, more than four times the next largest venue. The United States follows with 14, and Europe and South Korea each have 4, with Canada and India at 2 apiece. Anyone doing freedom-to-operate work in this field needs to search Chinese-language filings directly rather than relying on US or European databases alone.
US20160223259A1, filed by SECO/WARWICK S.A. in 2016, claims a multi-chamber furnace for vacuum carburizing and quenching with vertically arranged heating, carburizing and diffusion chambers inside a shared vacuum space, gas-tight divisions, a graphite heating system, and a stepping feed mechanism for continuous workpiece throughput. It matters because it is a representative example of the equipment-side claims that sit alongside the more heavily cited gas-chemistry patents in this space, and its chamber-arrangement and feed-mechanism claims define one boundary that furnace designers need to check against.
The IPC composition shows heavy concentration in core heat treatment (C21D, 88.8% of records) and coating (C23C, 48.3%), while furnace accessories (F27D), non-ferrous treatment (C22F), corrosion control (C23F) and general metalworking automation (B23P) each sit under 10%. Those lower-density classes are the more promising areas to search before filing, since claim space there is comparatively open relative to the core process classes.
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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.