Defining Terms and Distinguishing Trademarks in Nitriding

Defining Terms and Distinguishing Trademarks in Nitriding


Welcome to our exploration of Nitriding, it’s key terminology, and varied trademarks. This advanced thermo-chemical heat treating technique plays a crucial role in enhancing the durability and performance of metal parts. Widely used in industries such as automotive, oil & gas, defense & military, medical, industrial machinery, and forestry & mining, Nitriding is valued for its ability to significantly improve the wear resistance and corrosion protection of ferrous (iron-based) metals. This guide will provide you with a clear understanding of the various terms and trade names associated with this innovative surface treatment method.

Nitriding’s widespread use and adaptation across different regions and industries illustrate its global reach and versatility. In this article, we will focus on cyanate-based (non-toxic) ferritic Liquid (salt bath) Nitrocarburizing (or LNC for short), a prominent form within this category. While there are other forms such as Gas Nitriding, Plasma Nitriding, and austenitic Liquid Salt Bath Nitriding, each with unique chemistries like cyanide-based (toxic) solutions, our discussion will primarily concentrate on the cyanate-based (non-toxic) processes due to their prevalence and significance in current applications.

Demystifying Nitriding: Core Terminology Explained


A foundational term in the world of metal treatment. Nitrocarburizing involves enriching the surface of a metal part with nitrogen and carbon. This dual infusion helps create a hard, wear-resistant layer, or hardened “case” on the metal component, making it more durable under operational stresses. Nitrocarburizing is what we do at Nitrera. 


This process, related but distinct from nitrocarburizing, involves only the addition of nitrogen to the metal's surface. Technically the Nitriding process is used less frequently, but the term nitriding is often used interchangeably with terms for newer methods like liquid and gas nitrocarburizing due to evolving industry practices. Nitriding is not what we do at Nitrera, we do nitrocarburizing, but we too commonly call it “nitriding”. 

Ferritic Nitrocarburizing (FNC):

The term FNC specifically highlights that the process is conducted at a temperature in the ferritic range which is generally <1100°F (593°F). The ferritic temperature range, which includes room temperature, is considered a low process temperature, avoiding unwanted phase change of the materials crystalline grain structure. Most Nitriding & Nitrocarburizing (both gas & liquid) processes operate in the ferritic temperature range. Gas Nitrocarburizing is sometimes marketed as “FNC” in a way that invites you to believe that FNC is a gas only process, which it is not. Most nitriding & nitrocarburizing processes operate in the ferritic phase. Ferritic Nitrocarburizing is what we do at Nitrera.

Austenitic Nitrocarburizing (ANC):

The term ANC specifically highlights that the process is conducted at a higher temperature, generally  >1100°F (593°F). At this temperature, there may be (depending on alloy content) some phase change to austenite at the surface. In conventional heat treating, a temperature of at least 1330°F is required to form austenite, but with the added thermo-chemical energy of nitriding present at the surface of the component, this temperature threshold is reduced. Austenitic Nitrocarburizing is NOT what we do at Nitrera.

Salt Bath Nitrocarburizing (SBN):

As the name suggests, this process uses a salt bath (a liquid atmosphere) to apply the nitrocarburizing treatment. The use of a salt medium allows for controlled and even distribution of nitrogen and carbon into the surface. The “salt” is not table salt (sodium-chloride), but rather other salts which often include sodium-carbonate, potassium-carbonate, and sodium-cyanate. These chemical compounds are generally non-toxic, and are classified as irritants. The salt-mix (the solution) is heated in a vessel until it is molten. The homogeneous melt point (the eutectic temperature) is usually >900°F (480°C). Salt Bath Nitrocarburizing is what we do at Nitrera. 

Liquid Nitrocarburizing (LNC) / Liquid Nitriding:

These terms emphasize the use of liquid atmosphere (salt baths), in order to make the distinction from the gaseous atmosphere used in gas nitriding or nitrocarburizing processes. Liquid Nitrocarburizing is what we do at Nitrera.

Controlled Liquid Ion Nitrocarburizing (CLIN):

Highlighting precision & control over the process, offering tailored outcomes that are critical for high-specification components. Controlled Liquid Ion Nitrocarburizing is what we do at Nitrera.

Black Nitride:

Notable for its striking black appearance and enhanced corrosion protection features, this term highlights the black oxide (often called the Quench or Q step) that is common in the salt bath nitrocarburizing process. Although technically optional, the black-oxide ‘passivation’ step is standard in the liquid salt bath process. Regarding gas nitriding, a black oxide finish may or may not be an option, may cost extra, will likely not look as black or consistant from part-to-part & batch-to-batch, and will likely not offer as much corrosion resistance. Black Nitride is what we do at Nitrera.

Conclusion: We call it LNC. You may call it SBN, CLIN, FNC, Nitriding or Nitrocarburizing. Either way, it is what we do, and what we are passionate about.

Trade Names and Special Salt Mixes in LNC

The world of Liquid Salt Bath Nitrocarburizing is rich with various trade names, each offering unique formulations and benefits. Understanding these can help in selecting the right process for specific industrial needs.

  • Arcor: This is a well-known name in LNC, popular for its range of salt mix formulations. Arcor treatments are designed to enhance corrosion resistance, surface hardness.
  • Melonite: Renowned for increasing the hardness and corrosion resistance of steel, Melonite treatments are often used in firearms manufacturing and automotive applications.
  • Durferrit: Specialized in LNC solutions, Durferrit provides treatments that are tailored for exceptional wear resistance and performance under high-stress conditions.
  • Tuftride: Celebrated for its ability to improve fatigue strength and wear resistance, Tuftride processing is favored in heavy machinery and automotive industries.
  • Sursulf: Known for its unique surface protection capabilities, Sursulf treatments are used in situations where additional corrosion protection is necessary.
  • Tenifer: This trade name is synonymous with longevity and durability, offering treatments that significantly extend the life of metal components.
  • Kolene: Recognized for its expertise in providing LNC solutions, Kolene treatments are used to achieve strong and corrosion-resistant metal surfaces.
  • Delamin: Known for advanced surface modification solutions, Delamin enhances both the aesthetic and functional qualities of metal parts.
  • Oxynit: This brand is noted for enhancing oxidation resistance as well as nitrocarburization, offering a dual benefit that is valuable in high-temperature environments.

These trade names are not just labels but represent a vast landscape of chemistry and application-specific solutions that cater to a wide range of industries. Each brand has developed its unique formulations that optimize the performance of the treated metals, thereby enabling manufacturers to meet stringent quality and durability requirements.

Addressing Common Misconceptions

In the complex field of metal surface treatments, misconceptions can lead to the selection of inappropriate processes, affecting the performance and longevity of components. Here, we clarify some of the most common misunderstandings:

  • Night Riding: A humorous yet common misnomer, this term obviously has nothing to do with metal treatments. It's essential to recognize and correct such playful variations to maintain professional standards in communication.
  • Titanium Nitride (TiN) Coating vs. Nitriding: Titanium nitride (TiN) coating is a thin film deposited onto the surface of metal components through a physical vapor deposition (PVD) process. This coating provides excellent hardness, wear resistance, and aesthetic appeal, often used in decorative applications and cutting tools. However, it should not be confused with nitriding, which is a thermo-chemical diffusion process that modifies the surface layer of ferrous metals by introducing nitrogen. While TiN coating and nitriding both enhance surface properties, they differ significantly in their application methods, material compatibility, and the depth of modification they provide.
  • Carbonitriding vs. Nitrocarburizing: While both processes involve the addition of carbon & nitrogen, carbon nitriding operates at much higher temperatures (~1550°F / 850°C) and incorporates much more carbon into the metal surface compared to nitrocarburizing. This results in different wear and fatigue characteristics. Most importantly, the high temperature of the process and subsequent quenching induce major dimensional change (distortion) compared to Nitrocarburizing. 
  • Nitrating vs. Nitriding: Nitrating is a chemical process that involves introducing nitro groups (-NO2) into a molecule, often used in making explosives or pharmaceuticals, and should not be confused with nitriding, which is a thermo-chemical heat treatment process for hardening ferrous metal surfaces.
  • Boron-Nitride Spray Coating vs. Nitriding: It's crucial to distinguish between boron-nitride spray coating and nitriding, as they serve different purposes and offer distinct benefits. Boron-nitride spray coating involves applying a thin layer of boron nitride onto the surface of a substrate to provide lubricity, thermal conductivity, and electrical insulation. This coating is often used in high-temperature applications where traditional lubricants would break down. In contrast, nitriding is a surface hardening process that diffuses nitrogen into the surface of ferrous metals, increasing their hardness, wear resistance, and corrosion resistance. While boron-nitride spray coating focuses on enhancing surface properties such as lubricity and thermal conductivity, nitriding primarily aims to improve the mechanical properties of metal components. Understanding the differences between these processes is essential for selecting the most suitable surface treatment method for specific applications.

By dispelling these myths and clarifying the terminology, we ensure that stakeholders are well-informed and capable of making the best decisions regarding the treatment processes for their specific needs.

The Impact of Chemistry in LNC

Chemistry plays a critical role in the effectiveness of Liquid Salt Bath Nitrocarburizing. The choice between cyanate-based and cyanide-based chemistries, for example, can significantly affect the outcome of the nitrocarburizing process. Cyanate-based solutions are generally preferred for their low toxicity and environmental impact compared to cyanide-based solutions. 

At Nitrera, we use cyanate-based (cyanide free) salt bath solutions to perform the LNC process. Compared to cyanide-based liquid nitrocarburizing and gas nitrocarburizing, cyanate-based LNC is much better for human life and the environment owing to reduced toxic emissions & safer handling (by avoiding ammonia gas & cyanides) and a closed system whereby salts are reused & recycled indefinitely. 


Do you have more questions about LNC or looking to enhance the performance and durability of your metal components? Explore the diverse world of Liquid Salt Bath Nitrocarburizing with us. Contact our experts at Nitrera to discuss how our LNC solutions can be tailored to meet your specific needs.

Q vs QP vs QPQ Application Table

Nitride & Quench
(Standard process)
Nitride & Quench + Polish
Nitride & Quench +
Polish + Quench
Case Hardened Surface to 55HRC+1

Reduces Friction & Adhesion by up to 60%

Black Oxide (Quench) for Corrosion Resistance & Aesthetics.
Same as Q, plus a Polishing step which restores the original finish, and increases surface luster.
Same as QP, plus reimmersion into the oxidizing (Quench) salt bath to further enhance corrosion resistance.
Price & Delivery
Lowest cost & fastest delivery
Marginal increase in cost & delivery time
Highest cost & delivery time
Surface Roughness (RA)2
≤32µin (0.8µm)

Nitriding can increase RA up to ~32µin (0.8µm) total
≤16µin (0.4µm)

QP restores RA to ~8-16µin  (0.2-0.4µm)

RA can be restored to ~2µin (0.05µm) by hand polishing or other means.
Same as QP
Appearance / Aesthetics
Deep matte finish

Some material may be aesthetically affected by brown/red iron oxides (particularly stainless steels and cast iron)
Satin Luster

Very high quality & consistent appearance from part to part & batch to batch.

Polishing removes brown oxides and other surface contamination & visible defects.
Same as QP but with further handling and processing there is decreased part to part & batch to batch consistency of appearance.
Corrosion Resistance
(Compared to Raw / un-Nitrided Material)
Carbon, low-alloy & tool steels: Tremendous increase3

Martensitic stainless steels: Moderate increase

Nodular irons: Slight increase

Precipitation hardened stainless steels: Unchanged

Ferritic & Austenitic stainless steels: Decreased
Carbon, low-alloy & tool steels: Same as Q

Martensitic stainless steels: Same as Q

Nodular irons: Same as Q

Precipitation hardened stainless steels: Reduced compared to Q

Ferritic & Austenitic stainless steels: Further reduced compared to Q
Carbon, low-alloy & tool steels: Potentially better than Q & QP

Martensitic stainless steels: Likely better than Q

Nodular irons: Same as Q

Precipitation hardened stainless steels: Likely better than Q

Ferritic & Austenitic stainless steels: Significantly better than Q
Best Choice
Any material needing surface hardness, yet surface roughness does not need to be <32µin (0.8µm), and corrosion resistance & aesthetics are not critical.
Surface Roughness (RA) of <32µin (0.8µm) required. E.g.: seal surfaces, cylinder bores, etc. 

Components with high-spec aesthetic requirements. E.g.: Firearms, tools, etc.
Same as QP 

Stainless steels if corrosion resistance is critical  

Everything else if the additional cost is worth it.

1 55-60HRC for Carbon Steels, 60-70HRC for Low-alloy Steels, 70HRC+ for Stainless Steels
2 Nitriding is not expected to increase surface roughness (RA) where the starting roughness is >32µin (0.8µm)
3 Up to ~400hr ASTM B117 salt spray test