Ultralow friction of copper by a green water-based lubricant containing phytic acid

Biodegradable ion-conductive polyvinyl alcohol/okra polysaccharide composite films for fast-response respiratory monitoring sensors

Polyvinyl alcohol (PVA) and okra polysaccharide (OP) are biodegradable polymers with high hydrophilicity and good biocompatibility with potential for use as flexible humidity-sensitive materials. Herein, biodegradable flexible composite films (named POP films) were prepared from PVA, OP, and phytic acid using a solution-casting method based on. POP films exhibited excellent mechanical strength, flexibility, flame retardancy, water resistance, humidity response, and humidity-sensing characteristics. Notably, the POP humidity sensors exhibited a hysteresis value of 1.88 % relative humidity for the adsorption and desorption processes and good sensitivity over a wide humidity range of 35-95 %. In addition, the humidity sensor distinguished the frequency of nose breathing, and its response and recovery times were 0.9 and 1.98 s, respectively. The excellent performance of POP sensors in monitoring humidity and human respiratory rates demonstrates the sensor's potential for wearable smart devices.

Tribological Aspects of Sheet Titanium Forming

Friction, wear, and lubrication are inherent to all metal-forming processes. Unfortunately, they are particularly troublesome when forming titanium materials, which tend to form titanium buildup on the working surfaces of the forming tools. Lubrication is one of the most effective ways to separate contacting surfaces and eliminate galling, thus reducing tool wear. The paper presents the tribological aspects of titanium sheets forming using environmentally friendly lubricants with the addition of boric acid. The lubricant's effectiveness was assessed on the basis of technological tests, such as the strip drawing test, the Erichsen cupping test, and the formation of spherical drawn parts in industrial conditions. Moreover, the results of the numerical simulation of forming a titanium hat-shaped part are presented. Numerical calculations of forming processes were performed using the PamStamp 2G system based on the finite element method. Both experiments and numerical analyses showed the positive effect of lubricants with boric acid on sheet titanium forming.