Boriding is a thermochemical diffusion process that hardens a metal surface by introducing boron atoms into it, producing a hard boride layer that resists abrasive wear far better than the base metal alone. Most patent claims in this field target the specific powder or paste composition used to deliver the boron, because small changes in boron source, diluent and activator ratios materially change layer thickness, hardness profile and brittleness. That is why the most-cited prior art in this dataset, such as US6478887B1, centres on composition claims rather than furnace design or process control.

The assignee base in this dataset is fragmented: only five co-assignee pairs appear across the 79 tracked families, and even the strongest pairing shares just two records. Historically active filers include BWT LLC, Hughes Tool Company and university-affiliated groups, but none of the tracked assignees show any filings in the most recent year captured. This suggests the field is currently held by legacy filers rather than an active corporate leader, and a fresh entrant may find more room to establish position than the citation counts alone would suggest.

Filing activity in this dataset rose to 12 records in 2018, the highest point in the tracked window, and has not recovered since; the midpoint year 2022 shows zero recorded filings. This pattern is consistent with a technology where the core composition space — boron source, diluent, activator and sintering agent ratios — was substantially claimed by the late 2010s, leaving less open ground for subsequent filers. It is worth noting that publication lags filing by roughly eighteen months, so the most recent one to two years in any dataset will always understate true activity, but the multi-year flatness here goes beyond what that lag alone would explain.

C23C, covering coating and surface deposition, appears in every one of the 79 records in this dataset and is the primary classification for boriding and diffusion coating claims. C21D (heat treatment of metals) and C22C (alloys) are useful secondary classes, appearing in 17 and 9 records respectively. Downstream application classes such as B32B (laminates), E21B (drilling) and F16L (pipe fittings) are worth checking too, since they capture claims on the components the coating protects rather than the coating chemistry itself.

The classification data shows heavy concentration in core C23C coating claims but comparatively thin coverage in adjacent application areas: B32B laminates, E21B drilling components and F16L pipe fittings each register only single-digit filing counts. Combined process claims that integrate boriding directly with heat-treatment steps, and boron source chemistries beyond the common B4C or amorphous boron options, also appear underexplored relative to the density of pure composition claims. A first claim targeting one of these narrower, less-crowded branches faces meaningfully less prior art than a new composition claim would.