The production of cemented carbide alloys faces significant challenges in preventing damage to delicate green bodies during manufacturing. As a critical material in high-performance applications like industrial cutting tools, cemented carbide offers exceptional hardness, wear resistance, and thermal stability, maintaining its properties even at extreme temperatures. However, traditional methods often result in green bodies breaking or sustaining flaws during demolding and handling, leading to costly economic losses and quality defects. A breakthrough process introduces a low-pressure forming technique that leverages a protective sleeve, ensuring intact workpieces and enhanced efficiency.

This innovative low-pressure forming process begins with an optimized mixing phase. Metal powders, including tungsten carbide and cobalt compounds, are combined with a binder system in a heated mixer at temperatures ranging from 100 to 120°C for 30 to 45 minutes. The binder comprises paraffin wax, plasticizers, and stearic acid in carefully balanced proportions: 50-80% wax, 5-20% plasticizers, and 5-25% stearic acid by mass. This step creates a viscous, flowable mixture ideal for injection, enhancing mold-filling properties without compromising structural integrity.

Subsequently, the mold preparation stage incorporates a unique protective feature. A mold cavity is fitted with a polysiloxane-based sleeve, which firmly adheres to the inner walls. This sleeve is approximately 2-3 mm thick and extends 7-10 mm beyond the cavity for easy access. To boost durability, the sleeve's polymer blend is reinforced with silicon carbide nanofibers and polyaromatic amide short fibers, improving impact resistance and compression strength. The fiber additives, accounting for 16-20% of the sleeve volume by a 1:1 to 1.2:1 ratio, transition to powder at higher temperatures without affecting the final product. Pull rods embedded into the sleeve sides facilitate seamless extraction later in the process.

For formation, the mixture undergoes low-pressure injection into the sleeved mold at carefully controlled parameters, with temperatures of 65-70°C and pressures of 2-4 MPa. This gentle approach minimizes stress on the green body compared to conventional high-pressure methods, ensuring uniform shape filling and reducing internal defects. Crucially, the sleeve itself withstands the injection environment, providing consistent protection without degradation during this phase.

Demolding represents a critical innovation where risks are mitigated by leveraging the sleeve. After cooling to room temperature, operators use the pull rods to extract the encased green body directly, bypassing direct handling that could cause fractures. Tools grip the sleeve rather than the green body, which prevents surface marks, cracks, and breakages—especially beneficial for elongated bodies used in precision tools. The sleeve also acts as a barrier against oxygen exposure and contamination, preserving surface quality throughout intermediate steps.

Debinding and pre-sintering occur with the sleeve still in place. Inside a sintering furnace, hydrogen flow initiates at 180-230 L/min to purge air. The temperature is then ramped: an initial stage at 80°C decomposes the polysiloxane sleeve over 120-160 minutes, generating gases like benzene and toluene that vent out with hydrogen. Fiber additives turn powdery and exit as well. Next, a ramped heating to 340-380°C dewaxes the binder over 110-160 minutes; optimal conditions include 350°C for 120min to allow slight carbon residue, aiding oxide reduction. A final pre-sinter at 750-850°C lasts 360 minutes, with pulsed hydrogen at 0.08-0.09 MPa to flush residual wax, ensuring pure carbide formation.

Vacuum sintering then consolidates the material at 1380-1400°C for 120-180 minutes under argon protection to prevent oxidation, followed by controlled cooling. Once the furnace reaches below 50°C, argon is evacuated, and the finished carbide bodies are discharged. This integrated sequence eliminates intermediate transfers, reducing contamination and breakage risks.

The process delivers substantial benefits across industries. By safeguarding green bodies through a removable sleeve, it boosts production yield by up to 98% in trials, cutting waste and costs in high-volume settings like tooling for automotive and aerospace sectors. Environmental gains emerge from reduced material scrappage and energy efficiency in the single-furnace debinding-sintering sequence. Moreover, the enhanced structural purity from pulsed hydrogen flushing ensures superior hardness and longevity in cutters and blades. Scaling this method could revolutionize powder metallurgy, with potential expansions to ceramics and other wear-resistant alloys, reinforcing sustainable advanced manufacturing.